Synthesis of 12-quinoline substituted andrographolide derivatives and their preliminary evaluation as anti-aggregation drugs

Keywords: 12-quinoline substituted andrographolide derivatives, ADP, andrographolide, anti-platelet aggregation, design, Inhibition rate, synthesis, Thrombin.

Natural products are endowed with various interesting pharmacophores and show various pharmacological activities.^[1–3] Therefore, natural products are the source of many lead compounds in drug development. Andrographolide 1 (Fig. 1), a natural product from the aerial parts of Andrographis paniculati Nees with up to 2.0%,^[4] shows rich biological activity such as anti-influenza virus,^[5] anti-hepatotoxic,^[6] anti-HIV,^[7] anti-cancer,^[8] anti-inflammatory^[9] and anti-hyperglycaemic activities.^[10] It is worth mentioning that, in our previous work, we reported firstly that andrographolide showed low anti-platelet aggregation activity due to its poor aqueous solubility. Owing to its high aqueous solubility, its sulfonate 2 (medicinal composition of Xiyanping) and succinate 3 (medicinal composition of Chuanhuning) (Fig. 1) had better anti-platelet aggregation activity, when adenosine diphosphate (ADP) was employed as inducer.^[11–13] Quinoline derivatives also exhibit a wide spectrum of biological activities such as anti-malarial,^[14] anti-bacterial,^[15] anti-cancer,^[16] anti-oxidant,^[17] anti-tuberculous,^[18] anti-parasitic,^[19] and anti-platelet aggregation (methyl liensinine, rhynchophylline, berberine) activities.^[20–22] Both andrographolide and quinoline are readily available pharmacophores and have been subjects in the search for new biologically active compounds. At the same time, there are practically no literature reports on anti-thrombotic or anti-platelet aggregation properties of hybrid derivatives with a combination of andrographolide and quinoline structures.

Fig. 1.  The structure of andrographolide 1 and its sulfonate 2 and succinate 3.

Thrombotic disease is a common and typical disease of cardiovascular disease, which seriously threatens human health and life quality.^[23] Inhibition of platelet aggregation is one of the most direct and effective strategies for the treatment of thrombosis.^[24–27] At present, there are quite a few kinds of anti-platelet aggregation drugs such as thromboxane A₂ (TXA₂) inhibitors (aspirin),^[28] ADP induction inhibitors (clopidogrel),^[29] phosphodiesterase (PDE) inhibitors (cilostazol),^[30] 5-hydroxytryptamine receptor antagonists (sarpogrelate),^[31] Ca²⁺ channel antagonists (flunarizine),^[32–34] platelet membrane glycoproteins (GP) Ⅱb/Ⅲa receptor inhibitors (tirofiban),^[35] and the protease active receptor-1 (PAR-1) antagonist vorapaxar sulfate.^[36,37] However, these drugs present many drawbacks in clinical treatment to some extent, such as excessive bleeding, allergic reactions, nausea, dyspnea, neutropenia, aplastic anaemia and thrombocytopenia.^[38–43] Therefore, it has been a research focus to develop new skeleton compounds for inhibition of platelet aggregation in recent years.

The purpose of this work was to develop accessible and effective methods to construct compounds with novel high activity and no obvious cell toxicity platelet aggregation from andrographolide and quinolines.

We successfully designed the synthetic route for the new skeleton compounds 9 with a combination of andrographolide and quinolines, shown in Scheme 1. Initially, andrographolide 1 underwent dehydration with activated aluminium oxide (neutral) to transform into dehydroandrographolide 4.^[44] Afterwards, the 3,19-OH groups of 4 were protected as isopropylidenes with 2,2-dimethoxypropane with pyridinium p-toluenesulfonate (PPTS) to yield 5.^[45] Compound 5 was degraded to key intermediate 6 by selective oxidation of the C-12,13 olefin bond with KMnO₄.^[46] Compounds 8 were synthesized from key intermediate 6 by reacting with 2-methylquinolines 7 in the presence of Fe(OAc)₂/trifluoroacetic acid (TFA) and deprotection with AcOH.^[47] To increase water solubility, two molecules of carboxylate were introduced into intermediates 8 to prepare a series of target derivatives 9 (12-quinoline substituted andrographolide derivatives).

Scheme 1.  Synthetic route for compound 9. Reagents and conditions: (a) activated alumina (neutral), anhydrous pyridine, 100°C, 12 h, 92% yield; (b) 2,2-dimethoxy propane, PPTS (cat.), toluene/dimethyl sulfoxide 7:3, reflux, 3 h, 90% yield; (c) KMnO₄, THF, −5°C; (d) Fe(OAc)₂, TFA (trifluoroacetic acid), toluene, N₂, 100°C, 24 h, then AcOH/H₂O  3:1, room temperature (rt), 2 h; (e) DMAP (4-dimethylaminopyridine), Et₃N, anhydride (succinic anhydride for 9a and 9c-9q, maleic anhydride for 9b), CH₂Cl₂, rt, overnight, then KHCO₃.

In preliminary screening, the 12-quinoline substituted andrographolide derivatives showed pronounced anti-platelet aggregation activities in vitro by turbidimetric test.^[48] Thrombin and ADP were used as inducers for platelet aggregation. Vorapaxar sulfate and aspirin were selected as positive controls. The inhibition rate (IR) and IC₅₀ of compounds 9 in vitro were calculated and are summarized in Table 1.

Table 1.  Inhibition rate (IR) and IC₅₀ of target compounds 9 in vitro. Bold indicates highest activity.

As shown in Table 1, compared with the positive control drugs vorapaxar sulfate and aspirin, both andrographolide (IR 23.53% for thrombin; IR 27.64% for ADP) and compound 8a (IR 24.26% for thrombin; IR 22.79% for ADP) displayed low activities. However, compared with andrographolide and compound 8a, compounds 2, 3, 9a and 9b, which contain sulfonate, succinate or maleate, exhibited better activities. The inhibition rate increased by 10–20%. This revealed that enhancing water solubility is beneficial to improving activity. Comparing compound 2 with 3, or comparing 9a with 9b, we could confirm that succinic acid salinization could be the most beneficial to increase the activity of the derivatives. Therefore, in our current work, the derivatives were all succinated at 3,19-OH, shown in Scheme 1.

For thrombin as inducer, the IR of 4′-substituted quinoline derivates (9c–9f) was significantly lower than the 6′-substituted (9g–9l) and 7′-substituted (9m–9q) quinoline derivates, as well as for ADP as inducer. Comparing 9g–9l with 9m–9q, the activities of latter were higher than the former. For 9m–9q, the order of inhibition rate for thrombin was 9q (7′-OH) > 9o (7′-F) > 9p (7′-Cl) > 9m (7′-CH₃) > 9n (7′-OCH₃). Anti-platelet aggregation activities were higher slightly when electron-withdrawing groups (F, Cl) and hydroxyl were introduced. Among these, 9o and 9q showed superior platelet aggregation activities induced by thrombin. Especially, 9q (IR 54.31%, IC₅₀ 0.30 μM/L) was equivalent to the positive control drug vorapaxar sulfate. The order of IR for ADP was 9o (7′-F) > 9p (7′-Cl) > 9m (7′-CH₃) > 9n (7′-OCH₃) > 9q (7′-OH). Also, 9o and 9p, which possess electron-withdrawing groups at 7′-C, showed superior platelet aggregation activities. Of these, 9o (IR 55.73%, IC₅₀ 0.36 μM/L) was equivalent to the positive control drug aspirin.

Mouse fibroblast cells (L929) were used to evaluate the cell toxicity of target derivatives 9. The relative survival rate is shown in Table 2 and Fig. 2. The results revealed that most compounds had no significant cytotoxicity. Among them, the survival rate of 9m, 9o and 9q was higher than of aspirin at a dose of 10 μM/L.

Table 2.  The relative survival rate of target compounds 9 in vitro. Bold indicates highest survival rates.

Fig. 2.  The relative survival rate for target compounds 9 in vitro.

Through our efforts, based on the structure of the natural product andrographolide, a series of 12-quinoline substituted derivatives were designed and synthesized. In preliminary biological evaluation, these compounds showed strong anti-platelet aggregation activities in response to thrombin and ADP agonists and no significant cytotoxicity. Among them, compound 9o (IR 55.73%, IC₅₀ 0.36 µM/L) had the highest anti-platelet aggregation activity induced by ADP. Compound 9q (IR 54.31%, IC₅₀ 0.30 µM/L) showed the highest anti-platelet aggregation activity induced by thrombin. In addition, both 9o and 9q had low cell toxicities at doses of 10 and 100 µM/L. The most active compounds were selected to be prepared for further studies such as bleeding time and mechanisms of action.

Infrared spectra were recorded on a Nicolet Avatar-370 spectrometer in KBr (ν in cm⁻¹). Melting points were measured on a Büchi B-540 capillary melting point apparatus and are uncorrected. Mass spectra (electrospray ionization mass spectrometry, ESI-MS) were obtained on a Thermo Finnigan LCQ-Advantage. High-resolution mass spectra (ESI-HRMS) were obtained on an Agilent 6210 time-of-flight (TOF) instrument. ¹H NMR and ¹³C NMR spectra were recorded on a Varian Mercury Plus-400 spectrometer (400 and 100 MHz) (δ in parts per million, J in hertz), using TMS as internal standard. Platelet aggregation rates were measured on an LG-PABER platelet aggregation apparatus (Beijing Shidi Scientific Instrument Co. Ltd, Beijing). All commercially available reagents and solvents were of analytical reagent grade and were used directly without further purification.

Compound 4: andrographolide 1 (100.00 g, 285.55 mmol) was dissolved in anhydrous pyridine (100 mL) and then activated alumina (neutral) (23.43 g, 228.42 mmol) was added. The mixture stirred at 100°C for ~12 h (reaction complete by TLC analysis). After cooling to room temperature, the reaction mixture was filtered and washed with CH₂Cl₂ (2 × 200 mL). The combined organic filtrate was concentrated under vacuum. The residue was purified by column chromatography (CH₂Cl₂/MeOH 20:1) and afforded product 4 dehydroandrographolide (69.82 g, 92.01%) as a white solid. Mp 203–204°C (lit.^[49] 204–205°C). IR (KBr) ν_max  3526, 3480, 2973, 2935, 2855, 1805, 1635, 1447, 1386, 1346, 1271, 1222, 1102, 1036, 974, 891 cm⁻¹. ¹H NMR (600 MHz, [D6]DMSO) δ 7.67 (1H, s, 14-H), 6.73 (1H, dd, J = 6.6 Hz, J = 15.8 Hz, 11-H), 6.13 (1H, d, J = 15.8 Hz, 12-H), 5.06 (1H, brs, 3-OH), 4.90 (2H, s, 15-H), 4.74 (1H, s, 17-Ha), 4.43 (1H, s, 17-Hb), 4.17 (1H, brs, 19-OH), 4.11 (1H, d, J = 11.8 Hz, 19-Ha), 3.54 (1H, d, J = 11.8 Hz, 19-Hb), 3.26–3.24 (1H, m, 3-H), 2.49 (1H, d, J = 6.6 Hz, 9-H), 2.05–1.22 (9H, m, 1,2,5,6,7-H), 1.10 (3H, s, 18-H), 0.87 (3H, s, 20-H). ¹³C NMR (100 MHz, [D6]DMSO) δ 173.2, 148.5, 138.8, 135.9, 131.5, 120.5, 110.1, 78.5, 71.0, 65.8, 61.2, 48.4, 43.2, 39.8, 36.8, 33.5, 28.3, 24.6, 19.6, 15.3 ppm.

Compound 5: dehydroandrographolide 4 (66.00 g, 198.68 mmol) was dissolved in a mixed solution of toluene and dimethyl sulfoxide (200 mL, 7:3) and then 2,2-dimethoxypropane (62.03 g, 595.85 mmol) and PPTS (cat.) (5.02 g, 20.05 mmol) were added. The mixture stirred at reflux for ~3–5 h (reaction complete by TLC analysis). After cooling to room temperature, water (200 mL) was added and the organic phase separated. Then, the aqueous phase was extracted with ethyl acetate (3 × 300 mL). The combined organic extract was washed with brine (3 × 200 mL) and dried over anhydrous Na₂SO₄, filtered and concentrated under vacuum. The residue was washed with ether (2 × 100 mL) at 5°C and crystallized from ethanol to give compound 5 (3-((E)-2-((4aR,6aR,7R,10aS,10bR)-3,3,6a,10b-tetramethyl-8-methylenedecahydro-1H-naphtho[2,1-d][1,3]dioxin-7-yl)vinyl)furan-2(5H)-one) as a light yellow solid (65.82 g, yield 89.01%). Mp 167–168°C. IR (KBr) ν_max 2875,1808, 1645, 1449, 1385, 1377, 1343, 1274, 1234, 1113, 1023, 971, 892 cm⁻¹. ¹H NMR (600 MHz, [D6]DMSO) δ 7.64 (1H, s, 14-H), 6.53 (1H, dd, J = 6.6 Hz, J = 15.7 Hz, 11-H), 6.16 (1H, d, J = 15.7 Hz, 12-H), 4.93 (2H, s, 15-H), 4.84 (1H, s, 17-Ha), 4.46 (1H, s, 17-Hb), 4.10 (1H, d, J = 11.7 Hz, 19-Ha), 3.52 (1H, d, J = 11.7 Hz, 19-Hb), 3.28–3.25 (1H, m, 3-H), 2.53 (1H, d, J = 6.6 Hz, 9-H), 2.07–1.28 (9H, m, 1,2,5,6,7-H), 1.23–1.22 (6H, m, 23,24-H), 1.09 (3H, s, 18-H), 0.91 (3H, s, 20-H). ¹³C NMR (100 MHz, [D6]DMSO) δ 171.2, 140.2, 138.4, 136.2, 131.6, 120.2, 115.9, 110.0, 77.5, 71.2, 65.6, 61.3, 48.5, 43.1, 39.6, 36.7, 33.3, 31.3, 26.6, 26.5, 24.3, 16.6, 13.3 ppm. MS (ESI) m/z (%)  373.2 ([M + H]⁺, 100%). HRMS (ESI) calcd for C₂₃H₃₃O₄ [M + H]⁺ 373.2301, found 373.2309.

Compound 6: compound 5 (62.00 g, 166.56 mmol) was dissolved in tetrahydrofuran (THF) (300 mL) and then KMnO₄ (52.60 g, 333.20 mmol) was added slowly at −5°C and the mixture stirred for 5 h until total consumption of compound 5. Then, the mixture was stirred at reflux for ~3–5 h (reaction complete by TLC analysis). After reaction, the mixture was filtered and the solvent was removed under vacuum. Then, CH₂Cl₂ (3 × 200 mL) was poured into the residue and stirred strongly for 30 min. The combined CH₂Cl₂ extract was washed with brine (3 × 100 mL) and dried over anhydrous Na₂SO₄, filtered and concentrated under vacuum. The residue was purified by column chromatography (light petroleum/ethyl acetate 2:1) and afforded product 6 ((4aR,6aR,7R,10aS,10bR)-3,3,6a,10b-tetramethyl-8-methylenedecahydro-1H-naphtho[2,1-d][1,3]dioxine-7-carbaldehyde) (38.98 g, 80.10%) as a white solid. Mp 134 −135°C. IR (KBr) ν_max 2975, 2825, 2720, 1748, 1645, 1449, 1385, 1378, 1343, 1269, 1234, 1123, 1023, 971, 892 cm⁻¹. ¹H NMR (600 MHz, [D6]DMSO) δ 9.72 (1H, d, J = 2.4 Hz, 11-H), 5.25 (1H, s, 12-Ha), 5.14 (1H, s, 12-Hb), 4.10 (1H, d, J = 11.9 Hz, 14-Ha), 3.52 (1H, d, J = 11.9 Hz, 14-Hb), 3.07–3.05 (1H, m, 3-H), 2.93 (1H, d, J = 2.4 Hz, 9-H), 2.07–1.28 (9H, m, 1,2,5,6,7-H), 1.22–1.21 (6H, m, 17,18-H), 1.09 (3H, s, 13-H), 0.91 (3H, s, 15-H). ¹³C NMR (100 MHz, [D6]DMSO) δ 205.1, 145.0, 115.8, 109.2, 77.6, 68.2, 65.6, 48.5, 43.1, 39.5, 36.7, 33.1, 31.3, 26.5, 26.4, 24.3, 15.6, 14.3 ppm. MS (ESI) m/z (%)  293.2 ([M + H]⁺, 100%). HRMS (ESI) calcd for C₁₈H₂₉O₃ [M + H]⁺ 293.2038, found 293.2048.

Compound 8 (8a is selected as an example): compound 6 (2.00 g, 6.84 mmol) was dissolved in dry toluene (20 mL) and then Fe(OAc)₂ (0.06 g, 0.34 mmol), 2-methylquinoline (1.16 g, 8.20 mmol) and TFA (0.08 g, 0.68 mmol) were added under N₂ at room temperature. The mixture was stirred at 100°C for 24 h until total consumption of compound 6. The mixture was then cooled to room temperature and the solvent was removed under reduced pressure. The residue was dissolved in a mixture of AcOH and H₂O (15 mL, 3:1) at room temperature for ~2 h. After reaction, sodium bicarbonate solution was added dropwise to neutralize the mixture. CH₂Cl₂ (3 × 40 mL) was poured into the mixture. The combined CH₂Cl₂ extract was washed with brine (3 × 30 mL) and dried over anhydrous Na₂SO₄, filtered and concentrated under vacuum. The residue was purified by column chromatography (CH₂Cl₂/MeOH  15:1) and afforded product 8a ((1R,2R,4aR,5R,8aS)-1-(hydroxymethyl)-1,4a-dimethyl-6-methylene-5-((E)-2-(quinolin-2-yl)vinyl)decahydronaphthalen-2-ol) (77.52%, 2.00 g) as a pale yellow solid. Mp 220–221°C. IR (KBr) ν_max 3527, 3470, 3256, 3102, 2983, 2945, 2825, 1635, 1447, 1396, 1348, 1271, 1232, 1112, 1036, 975, 886 cm⁻¹. ¹H NMR (600 MHz, [D6]DMSO) δ 8.22–8.07 (1H, m, 4′-H), 8.08–7.83 (3H, m, 5′,7′,8′-H), 7.62–7.60 (1H, m, 6′-H), 7.37 (1H, d, J = 8.3 Hz, 3′-H), 6.68 (1H, dd, J = 6.8 Hz, J = 15.8 Hz, 11-H), 6.54 (1H, d, J = 15.8 Hz, 12-H), 5.03 (1H, s, 13-Ha), 4.87 (1H, s, 13-Hb), 3.68 (1H, brs, 15-OH), 3.59 (1H, brs, 3-OH), 3.50 (1H, d, J = 11.8 Hz, 15-Ha), 3.31 (1H, d, J = 11.8 Hz, 15-Hb), 3.17–3.14 (1H, m, 3-H), 2.76 (1H, d, J = 6.8 Hz, 9-H), 2.10–1.20 (9H, m, 1,2,5,6,7-H), 1.11 (3H, s, 14-H), 0.83 (3H, s, 16-H). ¹³C NMR (100 MHz, [D6]DMSO) δ 156.4, 148.8, 148.1, 136.5, 130.5, 128.8, 128.0, 126.9, 126.0, 125.8, 125.1, 118.5, 110.1, 78.5, 65.8, 61.9, 47.4, 43.3, 39.9, 36.7, 33.3, 27.9, 24.7, 19.4, 15.0 ppm. MS (ESI) m/z (%) 378.2 ([M + H]⁺, 100%). HRMS (ESI) calcd for C₂₅H₃₂NO₂ [M + H]⁺ 378.2433, found 378.2445.

(1R,2R,4aR,5R,8aS)-1-(Hydroxymethyl)-1,4a-dimethyl-6-methylene-5-((E)-2-(4-methylquinolin-2-yl)vinyl)decahydronaphthalen-2-ol 8b (pale yellow solid, 74.25%, 1.99 g); mp 190–191°C. IR (KBr): ν_max 3527, 3453, 3104, 2973, 2945, 2925, 1635, 1447, 1363, 1343, 1276, 1230, 1037, 973, 893 cm⁻¹. ¹H NMR (600 MHz, [D6]DMSO) δ 8.10–7.74 (3H, m, 5′,7′,8′-H), 7.62–7.58 (1H, m, 6′-H), 7.17 (1H, s, 3′-H), 6.68 (1H, dd, J = 6.2 Hz, J = 15.7 Hz, 11-H), 6.55 (1H, d, J = 15.7 Hz, 12-H), 5.05 (1H, s, 13-Ha), 4.88 (1H, s, 13-Hb), 3.67 (1H, brs, 15-OH), 3.58 (1H, brs, 3-OH), 3.49 (1H, d, J = 11.8 Hz, 15-Ha), 3.32 (1H, d, J = 11.8 Hz, 15-Hb), 3.17–3.13 (1H, m, 3-H), 2.76 (1H, d, J = 6.2 Hz, 9-H), 2.61 (3H, s, 4′-CH₃), 2.10–1.18 (9H, m, 1,2,5,6,7-H), 1.08 (3H, s, 14-H), 0.80 (3H, s, 16-H). ¹³C NMR (100 MHz, [D6]DMSO) δ 157.4, 148.9, 146.8, 144.1, 130.5, 128.7, 128.2, 126.7, 126.0, 125.8, 125.2, 118.3, 109.1, 78.5, 65.8, 61.9, 47.4, 43.2, 39.8, 36.6, 33.2, 27.8, 24.8, 20.2, 19.6, 15.1 ppm. MS (ESI) m/z (%)  392.3 ([M + H]⁺, 100%). HRMS (ESI) calcd for C₂₆H₃₄NO₂ [M + H]⁺ 392.2589, found 392.2596.

(1R,2R,4aR,5R,8aS)-5-((E)-2-(4-Fluoroquinolin-2-yl)vinyl)-1-(hydroxymethyl)-1,4a-dimethyl-6-methylenedecahydronaphthalen-2-ol 8c (yellow solid, 71.48%, 1.93 g); mp 210–211°C. IR (KBr) ν_max 3525, 3456, 3106, 2957, 2948, 2925, 1655, 1446, 1382, 1346, 1277, 1233, 1032, 975, 885 cm⁻¹. ¹H NMR (600 MHz, [D6]DMSO) δ 8.07–7.74 (4H, m, 5′,6′,7′,8′-H), 7.07–7.00 (1H, m, 3′-H), 6.65 (1H, dd, J = 6.2 Hz, J = 15.7 Hz, 11-H), 6.54 (1H, d, J = 15.7 Hz, 12-H), 5.05 (1H, s, 13-Ha), 4.87 (1H, s, 13-Hb), 3.65 (1H, brs, 15-OH), 3.54 (1H, brs, 3-OH), 3.43 (1H, d, J = 11.8 Hz, 15-Ha), 3.32 (1H, d, J = 11.8 Hz, 15-Hb), 3.15–3.11 (1H, m, 3-H), 2.78 (1H, d, J = 6.2 Hz, 9-H), 2.13–1.13 (9H, m, 1,2,5,6,7-H), 1.04 (3H, s, 14-H), 0.84 (3H, s, 16-H). ¹³C NMR (100 MHz, [D6]DMSO) δ 167.2 (¹J_CF = 246.2 Hz), 156.4, 148.9, 148.5, 131.5, 129.0, 127.2, 125.7, 125.0, 120.8, 118.3 (²J_CF = 22.0 Hz), 109.1, 101.8 (²J_CF = 22.6 Hz), 78.7, 65.5, 61.6, 47.2, 43.3, 39.5, 36.3, 33.4, 27.3, 24.5, 19.1, 15.0 ppm. MS (ESI) m/z (%) 396.2 ([M + H]⁺, 100%). HRMS (ESI) calcd for C₂₅H₃₁FNO₂ [M + H]⁺ 396.2339, found 396.2348.

(1R,2R,4aR,5R,8aS)-5-((E)-2-(4-Chloroquinolin-2-yl)vinyl)-1-(hydroxymethyl)-1,4a-dimethyl-6-methylenedecahydronaphthalen-2-ol 8d (pale yellow solid, 69.75%, 1.96 g); mp 215–216°C. IR (KBr) ν_max 3527, 3446, 3105, 2977, 2945, 2927, 1638, 1445, 1384, 1347, 1274, 1233, 1033, 974, 885 cm⁻¹. ¹H NMR (600 MHz, [D6]DMSO) δ 8.62–8.58 (1H, m, 5′-H), 8.10–7.74 (3H, m, 6′,7′,8′-H), 7.57 (1H, s, 3′-H), 6.64 (1H, dd, J = 6.2 Hz, J = 15.7 Hz, 11-H), 6.54 (1H, d, J = 15.7 Hz, 12-H), 5.05 (1H, s, 13-Ha), 4.84 (1H, s, 13-Hb), 3.63 (1H, brs, 15-OH), 3.55 (1H, brs, 3-OH), 3.42 (1H, d, J = 11.8 Hz, 15-Ha), 3.32 (1H, d, J = 11.8 Hz, 15-Hb), 3.16–3.10 (1H, m, 3-H), 2.79 (1H, d, J = 6.2 Hz, 9-H), 2.13–1.14 (9H, m, 1,2,5,6,7-H), 1.02 (3H, s, 14-H), 0.82 (3H, s, 16-H). ¹³C NMR (100 MHz, [D6]DMSO) δ 156.4, 148.9, 147.8, 143.4, 133.4, 129.1, 127.2, 126.7, 125.6, 125.1, 124.2, 118.1, 109.0, 78.8, 65.5, 62.3, 47.3, 43.3, 39.5, 36.4, 33.3, 27.4, 24.5, 19.3, 15.1 ppm. MS (ESI) m/z (%) 412.2 ([M + H]⁺, C₂₅H₃₁³⁵ClNO₂, 100%), 414.2 ([M + H]⁺, C₂₅H₃₁³⁷ClNO₂, 33%). HRMS (ESI) calcd for C₂₅H₃₁³⁵ClNO₂ [M + H]⁺ 412.2043, found 412.2055; for C₂₅H₃₁³⁷ClNO₂ [M + H]⁺ 414.2014, found 414.2023.

2-((E)-2-((1R,4aS,5R,6R,8aR)-6-Hydroxy-5-(hydroxymethyl)-5,8a-dimethyl-2-methylenedecahydronaphthalen-1-yl)vinyl)quinolin-4-ol 8e (light yellow solid, 64.68%, 1.74 g); mp 195–196°C. IR (KBr) ν_max 3525, 3456, 3257, 3108, 2977, 2948, 2923, 1637, 1444, 1386, 1347, 1273, 1235, 1033, 975, 893 cm⁻¹. ¹H NMR (600 MHz, [D6]DMSO) δ 8.30–7.80 (3H, m, 5′,7′,8′-H), 7.72–7.59 (1H, m, 6′-H), 6.80 (1H, s, 3′-H), 6.65 (1H, dd, J = 6.2 Hz, J = 15.7 Hz, 11-H), 6.53 (1H, d, J = 15.7 Hz, 12-H), 5.35 (1H, brs, 4′-OH), 5.04 (1H, s, 13-Ha), 4.83 (1H, s, 13-Hb), 3.64 (1H, brs, 15-OH), 3.52 (1H, brs, 3-OH), 3.41 (1H, d, J = 11.8 Hz, 15-Ha), 3.34 (1H, d, J = 11.8 Hz, 15-Hb), 3.17–3.12 (1H, m, 3-H), 2.78 (1H, d, J = 6.2 Hz, 9-H), 2.12–1.19 (9H, m, 1,2,5,6,7-H), 1.06 (3H, s, 14-H), 0.90 (3H, s, 16-H). ¹³C NMR (100 MHz, [D6]DMSO) δ 166.3, 157.4, 149.2, 148.8, 130.8, 128.5, 127.1, 125.7, 125.2, 121.3, 117.3, 109.2, 102.4, 78.8, 65.4, 61.8, 47.6, 43.3, 39.4, 36.6, 33.3, 27.4, 24.4, 19.6, 15.0 ppm. MS (ESI) m/z (%)  394.2 ([M + H]⁺, 100%). HRMS (ESI) calcd for C₂₅H₃₂NO₃ [M + H]⁺ 394.2382, found 394.2392.

(1R,2R,4aR,5R,8aS)-1-(Hydroxymethyl)-1,4a-dimethyl-6-methylene-5-((E)-2-(6-methylquinolin-2-yl)vinyl)decahydronaphthalen-2-ol 8f (yellow solid, 74.62%, 2.00 g); mp 201–202°C. IR (KBr) ν_max 3528, 3453, 3107, 2948, 2935, 1645, 1457, 1387, 1349, 1274, 1233, 1034, 973, 885 cm⁻¹. ¹H NMR (600 MHz, [D6]DMSO) δ 8.21 (1H, d, J = 8.3 Hz, 4′-H), 7.92 (1H, d, J = 8.3 Hz, 8′-H) 7.62–7.58 (2H, m, 5′,7′-H), 7.17 (1H, dd, J = 8.3 Hz, J = 4.3 Hz, 3′-H), 6.70 (1H, dd, J = 6.2 Hz, J = 15.7 Hz, 11-H), 6.55 (1H, d, J = 15.7 Hz, 12-H), 5.07 (1H, s, 13-Ha), 4.85 (1H, s, 13-Hb), 3.69 (1H, brs, 15-OH), 3.59 (1H, brs, 3-OH), 3.51 (1H, d, J = 11.8 Hz, 15-Ha), 3.31 (1H, d, J = 11.8 Hz, 15-Hb), 3.18–3.15 (1H, m, 3-H), 2.70 (1H, d, J = 6.2 Hz, 9-H), 2.34 (3H, s, 6′-CH₃), 2.13–1.18 (9H, m, 1,2,5,6,7-H), 1.12 (3H, s, 14-H), 0.86 (3H, s, 16-H). ¹³C NMR (100 MHz, [D6]DMSO) δ 155.4, 148.7, 146.2, 137.1, 135.8, 130.5, 128.2, 126.7, 126.2, 125.8, 125.2, 118.4, 109.3, 78.7, 65.5, 61.6, 47.5, 43.4, 39.6, 36.7, 33.3, 27.4, 24.6, 20.3, 19.7, 15.3 ppm. MS (ESI) m/z (%) 392.3 ([M + H]⁺, 100%). HRMS (ESI) calcd for C₂₆H₃₄NO₂ [M + H]⁺ 392.2589, found 392.2597.

(1R,2R,4aR,5R,8aS)-1-(Hydroxymethyl)-5-((E)-2-(6-methoxyquinolin-2-yl)vinyl)-1,4a-dimethyl-6-methylenedecahydronaphthalen-2-ol 8g (pale yellow solid, 76.34%, 2.13 g); mp 206–207°C. IR (KBr) ν_max 3529, 3452, 3103, 2943, 2822, 1643, 1459, 1384, 1344, 1277, 1233, 1032, 972, 896 cm⁻¹. ¹H NMR (600 MHz, [D6]DMSO) δ 8.20–8.16 (1H, m, 4′-H), 7.78 (1H, d, J = 8.3 Hz, 8′-H), 7.39–7.32 (2H, m, 3′,7′-H), 7.17–7.09 (1H, m, 5′-H), 6.69 (1H, dd, J = 6.2 Hz, J = 15.7 Hz, 11-H), 6.54 (1H, d, J = 15.7 Hz, 12-H), 5.05 (1H, s, 13-Ha), 4.85 (1H, s, 13-Hb), 3.83 (3H, s, 6′-OCH₃), 3.67 (1H, brs, 15-OH), 3.58 (1H, brs, 3-OH), 3.50 (1H, d, J = 11.8 Hz, 15-Ha), 3.30 (1H, d, J = 11.8 Hz, 15-Hb), 3.17–3.14 (1H, m, 3-H), 2.77 (1H, d, J = 6.2 Hz, 9-H), 2.11–1.16 (9H, m, 1,2,5,6,7-H), 1.04 (3H, s, 14-H), 0.90 (3H, s, 16-H). ¹³C NMR (100 MHz, [D6]DMSO) δ 157.4, 154.7, 148.2, 143.1, 135.3, 130.4, 129.2, 125.5, 125.0, 122.5, 119.4, 109.2, 105.4, 78.9, 65.6, 61.3, 55.3, 47.4, 43.3, 39.3, 36.5, 33.3, 27.5, 24.7, 19.5, 15.1 ppm. MS (ESI) m/z (%) 408.3 ([M + H]⁺, 100%). HRMS (ESI) calcd for C₂₆H₃₄NO₃ [M + H]⁺ 408.2540, found 408.2549.

(1R,2R,4aR,5R,8aS)-5-((E)-2-(6-Fluoroquinolin-2-yl)vinyl)-1-(hydroxymethyl)-1,4a-dimethyl-6-methylenedecahydronaphthalen-2-ol 8h (yellow solid, 66.66%, 1.80 g); mp 216–217°C. IR (KBr) ν_max 3535, 3458, 3107, 2943, 2922, 1644, 1454, 1384, 1345, 1273, 1235, 1033, 972, 883 cm⁻¹. ¹H NMR (600 MHz, [D6]DMSO) δ 8.26–8.20 (1H, m, 4′-H), 7.93 (1H, d, J = 8.3 Hz, 8′-H), 7.39–7.32 (3H, m, 3′,5′,7′-H), 6.67 (1H, dd, J = 6.2 Hz, J = 15.7 Hz, 11-H), 6.53 (1H, d, J = 15.7 Hz, 12-H), 5.03 (1H, s, 13-Ha), 4.84 (1H, s, 13-Hb), 3.63 (1H, brs, 15-OH), 3.51 (1H, brs, 3-OH), 3.52 (1H, d, J = 11.8 Hz, 15-Ha), 3.32 (1H, d, J = 11.8 Hz, 15-Hb), 3.15–3.12 (1H, m, 3-H), 2.79 (1H, d, J = 6.2 Hz, 9-H), 2.20–1.13 (9H, m, 1,2,5,6,7-H), 1.03 (3H, s, 14-H), 0.91 (3H, s, 16-H). ¹³C NMR (100 MHz, [D6]DMSO) δ 160.3 (¹J_CF = 245.0 Hz), 155.4, 148.6, 147.1, 145.3, 135.9, 130.2, 125.6, 125.1, 121.5 (²J_CF = 21.2 Hz), 119.3, 109.5 (²J_CF = 21.3 Hz), 109.0, 78.7, 65.4, 62.3, 47.5, 43.1, 40.3, 36.2, 33.1, 27.2, 24.3, 19.3, 14.8 ppm. MS (ESI) m/z (%) 396.2 ([M + H]⁺, 100%). HRMS (ESI) calcd for C₂₅H₃₁FNO₂ [M + H]⁺ 396.2339, found 396.2349.

(1R,2R,4aR,5R,8aS)-5-((E)-2-(6-Chloroquinolin-2-yl)vinyl)-1-(hydroxymethyl)-1,4a-dimethyl-6-methylenedecahydronaphthalen-2-ol 8i (yellow solid, 70.32%, 1.99 g); mp 218–219°C. IR (KBr) ν_max 3515, 3458, 3102, 2942, 2921, 1646, 1454, 1385, 1346, 1273, 1234, 1035, 994, 883 cm⁻¹. ¹H NMR (600 MHz, [D6]DMSO) δ 8.26–8.20 (1H, m, 4′-H), 8.10 (1H, d, J = 8.3 Hz, 8′-H), 7.82 (1H, d, J = 8.3 Hz, 7′-H), 7.39 (1H, d, J = 8.3 Hz, 3′-H), 7.17–7.08 (1H, m, 5′-H), 6.64 (1H, dd, J = 6.2 Hz, J = 15.7 Hz, 11-H), 6.53 (1H, d, J = 15.7 Hz, 12-H), 5.02 (1H, s, 13-Ha), 4.82 (1H, s, 13-Hb), 3.66 (1H, brs, 15-OH), 3.54 (1H, brs, 3-OH), 3.46 (1H, d, J = 11.8 Hz, 15-Ha), 3.25 (1H, d, J = 11.8 Hz, 15-Hb), 3.16–3.10 (1H, m, 3-H), 2.82 (1H, d, J = 6.2 Hz, 9-H), 2.13–1.14 (9H, m, 1,2,5,6,7-H), 1.02 (3H, s, 14-H), 0.91 (3H, s, 16-H). ¹³C NMR (100 MHz, [D6]DMSO) δ 156.4, 148.4, 146.1, 135.4, 132.0, 131.4, 130.2, 128.7, 125.6, 125.1, 123.5, 119.8, 109.3, 78.8, 65.5, 61.3, 47.4, 43.6, 39.4, 36.2, 33.3, 27.2, 24.5, 19.2, 15.0 ppm. MS (ESI) m/z (%) 412.2 ([M + H]⁺, C₂₅H₃₁³⁵ClNO₂, 100%), 414.2 ([M + H]⁺, C₂₅H₃₁³⁷ClNO₂, 33%). HRMS (ESI) calcd for C₂₅H₃₁³⁵ClNO₂ [M + H]⁺: 412.2043, found 412.2057; for C₂₅H₃₁³⁷ClNO₂[M + H]⁺ 414.2014, found 414.2022.

(1R,2R,4aR,5R,8aS)-5-((E)-2-(6-Bromoquinolin-2-yl)vinyl)-1-(hydroxymethyl)-1,4a-dimethyl-6-methylenedecahydronaphthalen-2-ol 8j (yellow solid, 65.18%, 2.04 g); mp 241–242°C. IR (KBr) ν_max 3534, 3437, 3101, 2945, 2926, 1646, 1457, 1383, 1346, 1276, 1231, 1031, 974, 882 cm⁻¹. ¹H NMR (600 MHz, [D6]DMSO) δ 8.28–8.01 (4H, m, 4′,5′,7′,8′-H), 7.44 (1H, d, J = 8.3 Hz, 3′-H), 6.68 (1H, dd, J = 6.2 Hz, J = 15.7 Hz, 11-H), 6.54 (1H, d, J = 15.7 Hz, 12-H), 5.04 (1H, s, 13-Ha), 4.85 (1H, s, 13-Hb), 3.65 (1H, brs, 15-OH), 3.56 (1H, brs, 3-OH), 3.50 (1H, d, J = 11.8 Hz, 15-Ha), 3.31 (1H, d, J = 11.8 Hz, 15-Hb), 3.18–3.12 (1H, m, 3-H), 2.83 (1H, d, J = 6.2 Hz, 9-H), 2.14–1.15 (9H, m, 1,2,5,6,7-H), 1.03 (3H, s, 14-H), 0.90 (3H, s, 16-H). ¹³C NMR (100 MHz, [D6]DMSO) δ 156.1, 148.8, 148.4, 135.3, 133.1, 132.4, 129.8, 128.7, 125.5, 125.1, 123.5, 120.8, 109.3, 78.7, 65.3, 61.2, 48.4, 43.7, 40.4, 36.7, 33.4, 27.6, 24.4, 19.7, 15.2 ppm. MS (ESI) m/z (%) 456.2 ([M + H]⁺, C₂₅H₃₁⁷⁹BrNO₂, 100%), 458.2 ([M + H]⁺, C₂₅H₃₁⁸¹BrNO₂, 97%). HRMS (ESI) calcd for C₂₅H₃₁⁷⁹BrNO₂ [M + H]⁺: 456.1538, found 456.1547; for C₂₅H₃₁⁸¹BrNO₂ [M + H]⁺ 458.1518, found 458.1527.

2-((E)-2-((1R,4aS,5R,6R,8aR)-6-Hydroxy-5-(hydroxymethyl)-5,8a-dimethyl-2-methylenedecahydronaphthalen-1-yl)vinyl)quinolin-6-ol 8k (pale yellow solid, 57.62%, 1.55 g); mp 220–221°C. IR (KBr) ν_max 3532, 3464, 3105, 2946, 2924, 1643, 1452, 1385, 1346, 1273, 1235, 1032, 972, 885 cm⁻¹. ¹H NMR (600 MHz, [D6]DMSO) δ 8.06–8.00 (1H, m, 4′-H), 7.81 (1H, d, J = 8.3 Hz, 8′-H), 7.42–7.17 (3H, m, 3′,5′,7′-H), 6.68 (1H, dd, J = 6.2 Hz, J = 15.7 Hz, 11-H), 6.55 (1H, d, J = 15.7 Hz, 12-H), 5.35 (1H, s, 6′-OH), 5.05 (1H, s, 13-Ha), 4.84 (1H, s, 13-Hb), 3.64 (1H, brs, 15-OH), 3.55 (1H, brs, 3-OH), 3.43 (1H, d, J = 11.8 Hz, 15-Ha), 3.26 (1H, d, J = 11.8 Hz, 15-Hb), 3.17–3.13 (1H, m, 3-H), 2.84 (1H, d, J = 6.2 Hz, 9-H), 2.15–1.13 (9H, m, 1,2,5,6,7-H), 1.05 (3H, s, 14-H), 0.84 (3H, s, 16-H). ¹³C NMR (100 MHz, [D6]DMSO) δ 155.4, 154.1, 148.8, 143.1, 134.8, 130.2, 128.9, 125.6, 125.4, 125.0, 119.2, 111.3, 109.3, 78.7, 65.3, 61.7, 47.5, 43.6, 39.7, 36.5, 33.3, 27.4, 24.5, 19.3, 15.3 ppm. MS (ESI) m/z (%) 394.2 ([M + H]⁺, 100%). HRMS (ESI) calcd for C₂₅H₃₂NO₃ [M + H]⁺ 394.2382, found 394.2393.

(1R,2R,4aR,5R,8aS)-1-(Hydroxymethyl)-1,4a-dimethyl-6-methylene-5-((E)-2-(7-methylquinolin-2-yl)vinyl)decahydronaphthalen-2-ol 8l (yellow solid, 75.37%, 2.02 g); mp 213–214°C. IR (KBr) ν_max 3538, 3446, 3107, 2952, 2942, 1654, 1453, 1386, 1350, 1264, 1230, 1044, 978, 887 cm⁻¹. ¹H NMR (600 MHz, [D6]DMSO) δ 8.21 (1H, d, J = 8.2 Hz, 4′-H), 7.92–7.58 (3H, m, 5′,6′,8′-H), 7.33 (1H, dd, J = 8.2 Hz, J = 4.3 Hz, 3′-H), 6.66 (1H, dd, J = 6.2 Hz, J = 15.7 Hz, 11-H), 6.53 (1H, d, J = 15.7 Hz, 12-H), 5.02 (1H, s, 13-Ha), 4.88 (1H, s, 13-Hb), 3.65 (1H, brs, 15-OH), 3.59 (1H, brs, 3-OH), 3.50 (1H, d, J = 11.6 Hz, 15-Ha), 3.31 (1H, d, J = 11.6 Hz, 15-Hb), 3.16–3.11 (1H, m, 3-H), 2.80 (1H, d, J = 6.2 Hz, 9-H), 2.34 (3H, s, 7′-CH₃), 2.12–1.17 (9H, m, 1,2,5,6,7-H), 1.09 (3H, s, 14-H), 0.92 (3H, s, 16-H). ¹³C NMR (100 MHz, [D6]DMSO) δ 156.2, 148.8, 146.4, 139.1, 136.0, 130.5, 128.2, 127.1, 126.2, 125.5, 125.0, 117.6, 109.2, 78.5, 65.3, 62.1, 46.5, 43.1, 40.3, 36.7, 33.1, 27.7, 24.6, 21.3, 19.5, 15.1 ppm. MS (ESI) m/z (%) 392.3 ([M + H]⁺, 100%). HRMS (ESI) calcd for C₂₆H₃₄NO₂ [M + H]⁺ 392.2589, found 392.2598.

(1R,2R,4aR,5R,8aS)-1-(Hydroxymethyl)-5-((E)-2-(7-methoxyquinolin-2-yl)vinyl)-1,4a-dimethyl-6-methylenedecahydronaphthalen-2-ol 8m (pale yellow solid, 71.33%, 1.99 g); mp 232–233°C. IR (KBr) ν_max 3528, 3464, 3102, 2945, 2821, 1651, 1451, 1384, 1350, 1261, 1227, 1041, 975, 892 cm⁻¹. ¹H NMR (600 MHz, [D6]DMSO) δ 8.23 (1H, d, J = 8.2 Hz, 4′-H), 7.99–7.90 (1H, m, 5′-H), 7.35–7.22 (3H, m, 3′,6′,8′-H), 6.68 (1H, dd, J = 6.2 Hz, J = 15.7 Hz, 11-H), 6.54 (1H, d, J = 15.7 Hz, 12-H), 5.03 (1H, s, 13-Ha), 4.86 (1H, s, 13-Hb), 3.83 (1H, s, 7′-OCH₃), 3.64 (1H, brs, 15-OH), 3.58 (1H, brs, 3-OH), 3.47 (1H, d, J = 11.6 Hz, 15-Ha), 3.33 (1H, d, J = 11.6 Hz, 15-Hb), 3.14–3.10 (1H, m, 3-H), 2.83 (1H, d, J = 6.2 Hz, 9-H), 2.10–1.15 (9H, m, 1,2,5,6,7-H), 1.10 (3H, s, 14-H), 0.90 (3H, s, 16-H). ¹³C NMR (100 MHz, [D6]DMSO) δ 156.9, 151.2, 148.6, 147.4, 136.2, 129.5, 128.2, 125.5, 125.0, 117.6, 116.5, 109.2, 107.2, 78.7, 65.4, 62.5, 55.8, 46.5, 43.3, 40.3, 36.5, 33.4, 27.4, 24.3, 19.6, 15.0 ppm. MS (ESI) m/z (%) 408.2 ([M + H]⁺, 100%). HRMS (ESI) calcd for C₂₆H₃₄NO₃ [M + H]⁺ 408.2538, found 408.2548.

(1R,2R,4aR,5R,8aS)-5-((E)-2-(7-Fluoroquinolin-2-yl)vinyl)-1-(hydroxymethyl)-1,4a-dimethyl-6-methylenedecahydronaphthalen-2-ol 8n (yellow solid, 67.77%, 1.83 g); mp 209–210°C. IR (KBr) ν_max 3531, 3462, 3111, 2912, 1658, 1454, 1389, 1353, 1265, 1232, 1042, 973, 893 cm⁻¹. ¹H NMR (600 MHz, [D6]DMSO) δ 8.23–8.05 (1H, m, 4′-H), 8.03–7.95 (1H, m, 5′-H), 7.76–7.69 (1H, m, 8′-H), 7.37 (1H, d, J = 8.3 Hz, 3′-H), 7.13–7.03 (1H, m, 6′-H), 6.68 (1H, dd, J = 6.2 Hz, J = 15.7 Hz, 11-H), 6.54 (1H, d, J = 15.7 Hz, 12-H), 5.04 (1H, s, 13-Ha), 4.88 (1H, s, 13-Hb), 3.63 (1H, brs, 15-OH), 3.57 (1H, brs, 3-OH), 3.46 (1H, d, J = 11.6 Hz, 15-Ha), 3.31 (1H, d, J = 11.6 Hz, 15-Hb), 3.15–3.10 (1H, m, 3-H), 2.83 (1H, d, J = 6.2 Hz, 9-H), 2.10–1.19 (9H, m, 1,2,5,6,7-H), 1.04 (3H, s, 14-H), 0.90 (3H, s, 16-H). ¹³C NMR (100 MHz, [D6]DMSO) δ 163.6 (¹J_CF = 245.2 Hz), 157.2, 148.6, 147.4, 136.6, 130.5, 125.5, 125.0, 118.6, 116.8 (²J_CF = 21.2 Hz), 112.8 (²J_CF = 21.3 Hz), 109.1, 78.7, 65.4, 62.2, 47.5, 43.2, 40.4, 36.5, 33.3, 27.6, 24.5, 21.2, 19.3, 15.0 ppm. MS (ESI) m/z (%) 396.2 ([M + H]⁺, 100%). HRMS (ESI) calcd for C₂₅H₃₁FNO₂ [M + H]⁺ 396.2339, found 396.2351.

(1R,2R,4aR,5R,8aS)-5-((E)-2-(7-Chloroquinolin-2-yl)vinyl)-1-(hydroxymethyl)-1,4a-dimethyl-6-methylenedecahydronaphthalen-2-ol 8o (pale yellow solid, 64.31%, 1.82 g); mp 196–197°C. IR (KBr) ν_max 3526, 3468, 3112, 2923, 1650, 1455, 1383, 1354, 1263, 1232, 1043, 975, 885 cm⁻¹. ¹H NMR (600 MHz, [D6]DMSO) δ 8.24–8.15 (2H, m, 4′,5′-H), 7.96–7.69 (2H, m, 6′,8′-H), 7.36 (1H, d, J = 8.3 Hz, 3′-H), 6.66 (1H, dd, J = 6.2 Hz, J = 15.7 Hz, 11-H), 6.56 (1H, d, J = 15.7 Hz, 12-H), 5.05 (1H, s, 13-Ha), 4.85 (1H, s, 13-Hb), 3.66 (1H, brs, 15-OH), 3.57 (1H, brs, 3-OH), 3.43 (1H, d, J = 11.6 Hz, 15-Ha), 3.33 (1H, d, J = 11.6 Hz, 15-Hb), 3.14–3.10 (1H, m, 3-H), 2.83 (1H, d, J = 6.2 Hz, 9-H), 2.10–1.15 (9H, m, 1,2,5,6,7-H), 1.02 (3H, s, 14-H), 0.85 (3H, s, 16-H). ¹³C NMR (100 MHz, [D6]DMSO) δ 157.5, 148.8, 147.2, 136.3, 135.4, 129.5, 128.4, 126.1, 125.5, 125.3, 125.0, 118.9, 109.2, 78.8, 65.5, 62.3, 47.4, 43.3, 40.0, 36.4, 33.2, 27.7, 24.2, 19.3, 15.0 ppm. MS (ESI) m/z (%) 412.2 ([M + H]⁺, C₂₅H₃₁³⁵ClNO₂, 100%), 414.2 ([M + H]⁺, C₂₅H₃₁³⁷ClNO₂, 33%). HRMS (ESI) calcd for C₂₅H₃₁³⁵ClNO₂ [M + H]⁺ 412.2043, found 412.2058; for C₂₅H₃₁³⁷ClNO₂ [M + H]⁺ 414.2014, found 414.2026.

2-((E)-2-((1R,4aS,5R,6R,8aR)-6-Hydroxy-5-(hydroxymethyl)-5,8a-dimethyl-2-methylenedecahydronaphthalen-1-yl)vinyl)quinolin-7-ol 8p (pale yellow solid, 58.74%, 1.58 g); mp 224–225°C. IR (KBr) ν_max 3535, 3446, 3254, 2914, 1651, 1455, 1381, 1354, 1261, 1235, 1042, 976, 888 cm⁻¹. ¹H NMR (600 MHz, [D6]DMSO) δ 8.24–8.13 (1H, m, 4′-H), 8.04–7.98 (1H, m, 5′-H), 7.33–7.12 (3H, m, 3′,6′,8′-H), 6.67 (1H, dd, J = 6.2 Hz, J = 15.7 Hz, 11-H), 6.55 (1H, d, J = 15.7 Hz, 12-H), 5.35 (1H, brs, 7′-OH), 5.02 (1H, s, 13-Ha), 4.87 (1H, s, 13-Hb), 3.66 (1H, brs, 15-OH), 3.57 (1H, brs, 3-OH), 3.50 (1H, d, J = 11.6 Hz, 15-Ha), 3.31 (1H, d, J = 11.6 Hz, 15-Hb), 3.17–3.11 (1H, m, 3-H), 2.82 (1H, d, J = 6.2 Hz, 9-H), 2.04–1.12 (9H, m, 1,2,5,6,7-H), 1.05 (3H, s, 14-H), 0.92 (3H, s, 16-H). ¹³C NMR (100 MHz, [D6]DMSO) δ 158.3, 156.8, 151.1, 148.6, 136.2, 130.0, 125.5, 125.0, 123.3, 118.6, 116.3, 110.8, 109.2, 78.8, 65.5, 62.4, 47.4, 43.3, 40.1, 36.8, 33.5, 27.4, 24.7, 19.6, 15.1 ppm. MS (ESI) m/z (%) 394.2 ([M + H]⁺, 100%). HRMS (ESI) calcd for C₂₅H₃₂NO₃ [M + H]⁺ 394.2382, found 394.2393.

Compound 9 (9a is selected as an example): compound 8a (1.50 g, 3.98 mmol) and succinic anhydride (1.19 g, 15.9 mmol) (for 9b, maleic anhydride 1.56 g, 15.9 mmol) were dissolved in CH₂Cl₂ (30 mL). Then, DMAP (N,N-4-dimethylaminopyridine, 0.53 g, 4.38 mmol) and Et₃N (0.60 g, 5.97 mmol) were added under stirring. The mixture was stirred at room temperature overnight until no compound 8a was detected by TLC. After reaction, hydrochloric acid (4 M) was added dropwise to neutralize the mixture. CH₂Cl₂ (3 × 30 mL) was poured into the mixture. The combined CH₂Cl₂ extract was washed with brine (3 × 30 mL) and dried over anhydrous Na₂SO₄, filtered and concentrated under vacuum. The residue was dissolved in ethanol (10 mL) and then KHCO₃ saturated solution (1.1 equiv.) was slowly added, producing a large number of bubbles. The mixture changed gradually from clear to milky white and stirring was continued for 1 h until bubbling ceased. Last, the mixture was filtered, dried and crystallized from acetone to give potassium 4-(((1R,2R,4aR,5R,8aS)-2-(3-carboxypropanoyloxy)-1,4a-dimethyl-6-methylene-5-((E)-2-(quinolin-2-yl)vinyl)decahydronaphthalen-1-yl)methoxy)-4-oxobutanoate 9a (1.54 g, yield 62.86%, purity 96.2%) as an off white solid. IR (KBr) ν_max 3412, 3080, 2938, 2851, 1753, 1720, 1636, 1575, 1447, 1384, 1346, 1277, 1235, 1114, 1037, 973, 892 cm⁻¹. ¹H NMR (600 MHz, D₂O) δ 8.24–8.17 (1H, m, 4′-H), 8.06 -7.80 (3H, m, 5′,7′,8′-H), 7.61–7.55 (1H, m, 6′-H), 7.34 (1H, d, J = 8.3 Hz, 3′-H), 6.67 (1H, dd, J = 6.2 Hz, J = 15.4 Hz, 11-H), 6.54 (1H, d, J = 15.4 Hz, 12-H), 5.05 (1H, s, 13-Ha), 4.86 (1H, s, 13-Hb), 4.15 (1H, d, J = 11.8 Hz, 15-Ha), 4.01–3.95 (1H, m, 3-H), 3.83 (1H, d, J = 11.8 Hz, 15-Hb), 2.86–2.75 (9H, m, 9,18,19,22,23-H), 2.13–1.45 (9H, m, 1,2,5,6,7-H), 1.01 (3H, s, 14-H), 0.93 (3H, s, 16-H). ¹³C NMR (100 MHz, D₂O) δ 176.5, 176.1, 173.5, 173.1, 156.4, 148.8, 148.1, 136.5, 130.5, 128.8, 128.0, 126.9, 126.0, 125.8, 125.1, 118.5, 110.1, 75.5, 65.8, 61.9, 47.4, 43.3, 39.9, 36.7, 33.3, 32.6, 32.3, 32.0, 30.2, 27.9, 24.7, 21.9, 15.0 ppm. MS (ESI) m/z (%) 616.3 ([M + H]⁺, 100%). HRMS (ESI) calcd for C₃₃H₃₉NO₈K [M + H]⁺ 616.3659, found 616.3667.

Potassium (E)-4-(((1R,2R,4aR,5R,8aS)-2-((E)-3-carboxyacryloyloxy)-1,4a-dimethyl-6-methylene-5-((E)-2-(quinolin-2-yl)vinyl)decahydronaphthalen-1-yl)methoxy)-4-oxobut-2-enoate 9b: creamy white solid, 1.58 g, yield 65.02%, purity 96.8%. IR (KBr) ν_max 3422, 3084, 2934, 2853, 1753, 1634, 1575, 1446, 1383, 1343, 1275, 1233, 1114, 1032, 972, 891 cm⁻¹. ¹H NMR (600 MHz, D₂O) δ 8.25–8.19 (1H, m, 4′-H), 8.07–7.82 (3H, m, 5′,7′,8′-H), 7.63–7.52 (1H, m, 6′-H), 7.37–7.24 (3H, m, 19,23,3′-H), 6.65 (1H, dd, J = 6.2 Hz, J = 15.4 Hz, 11-H), 6.53 (1H, d, J = 15.4 Hz, 12-H), 6.21–6.09 (2H, m, 18,22-H), 5.05 (1H, s, 13-Ha), 4.85 (1H, s, 13-Hb), 4.15 (1H, d, J = 11.8 Hz, 15-Ha), 4.00–3.94 (1H, m, 3-H), 3.82 (1H, d, J = 11.8 Hz, 15-Hb), 2.83–2.73 (1H, m, 9-H), 2.16–1.45 (9H, m, 1,2,5,6,7-H), 1.04 (3H, s, 14-H), 0.91 (3H, s, 16-H). ¹³C NMR (100 MHz, D₂O) δ 167.7, 167.1, 166.6, 166.1, 156.7, 148.6, 148.4, 139.7, 139.0, 136.4, 131.2, 131.1, 130.5, 128.6, 128.0, 126.7, 126.0, 125.4, 125.0, 118.6, 110.0, 75.7, 65.5, 62.3, 47.6, 43.3, 39.2, 36.4, 33.5, 27.6, 24.4, 21.7, 15.2 ppm. MS (ESI) m/z (%) 612.3 ([M + H]⁺, 100%). HRMS (ESI) calcd for C₃₄H₄₁NO₈K [M + H]⁺ 612.3346, found 616.3359.

Potassium 4-(((1R,2R,4aR,5R,8aS)-2-(3-carboxypropanoyloxy)-1,4a-dimethyl-6-methylene-5-((E)-2-(4-methylquinolin-2-yl)vinyl)decahydronaphthalen-1-yl)methoxy)-4-oxobutanoate 9c: creamy white solid, 1.58 g, yield 65.00%, purity 95.9%. IR (KBr) ν_max  3422, 3084, 3124, 2938, 2856, 1755, 1723, 1636, 1573, 1443, 1386, 1348, 1274, 1237, 1117, 1033, 973, 894 cm⁻¹. ¹H NMR (600 MHz, D₂O) δ 8.20–7.84 (3H, m, 5′,7′,8′-H), 7.62–7.57 (1H, m, 6′-H), 7.15 (1H, s, 3′-H), 6.69 (1H, dd, J = 6.2 Hz, J = 15.7 Hz, 11-H), 6.65 (1H, d, J = 15.7 Hz, 12-H), 5.05 (1H, s, 13-Ha), 4.87 (1H, s, 13-Hb), 4.14 (1H, d, J = 11.8 Hz, 15-Ha), 4.00–3.93 (1H, m, 3-H), 3.85 (1H, d, J = 11.8 Hz, 15-Hb), 2.86–2.74 (9H, m, 9,18,19,22,23-H), 2.61 (3H, s, 4′-CH₃), 2.17–1.49 (9H, m, 1,2,5,6,7-H), 1.04 (3H, s, 14-H), 0.90 (3H, s, 16-H). ¹³C NMR (100 MHz, D₂O) δ 176.2, 176.0, 173.6, 173.4, 157.5, 148.6, 146.7, 144.6, 130.7, 128.4, 128.5, 126.3, 126.0, 125.5, 125.1, 118.2, 109.1, 75.5, 65.9, 61.4, 47.3, 43.4, 39.5, 36.3, 33.2, 32.3, 32.0, 31.8, 30.1, 27.2, 24.5, 21.7, 20.3, 15.1 ppm. MS (ESI) m/z (%) 630.2 ([M + H]⁺, 100%). HRMS (ESI) calcd for C₂₄H₄₁NO₈K[M + H]⁺ 630.2469, found 630.2483.

Potassium 4-(((1R,2R,4aR,5R,8aS)-2-(3-carboxypropanoyloxy)-5-((E)-2-(4-fluoroquinolin-2-yl)vinyl)-1,4a-dimethyl-6-methylenedecahydronaphthalen-1-yl)methoxy)-4-oxobutanoate 9d: off white solid, 1.58 g, yield 62.70%, purity 96.8%. IR (KBr) ν_max 3418, 3081, 2933, 2854, 1757, 1722, 1634, 1576, 1444, 1387, 1346, 1274, 1237, 1114, 1036, 994, 886 cm⁻¹. ¹H NMR (600 MHz, D₂O) δ 8.17–7.85 (4H, m, 5′,6′,7′,8′-H), 7.14 (1H, d, J = 4.3 Hz, 3′-H), 6.68 (1H, dd, J = 6.2 Hz, J = 15.4 Hz, 11-H), 6.55 (1H, d, J = 15.4 Hz, 12-H), 5.04 (1H, s, 13-Ha), 4.84 (1H, s, 13-Hb), 4.16 (1H, d, J = 11.8 Hz, 15-Ha), 4.07–3.99 (1H, m, 3-H), 3.84 (1H, d, J = 11.8 Hz, 15-Hb), 2.83–2.72 (9H, m, 9,18,19,22,23-H), 2.15–1.46 (9H, m, 1,2,5,6,7-H), 1.04 (3H, s, 14-H), 0.87 (3H, s, 16-H). ¹³C NMR (100 MHz, D₂O) δ 176.6, 176.2, 173.4, 173.0, 167.3 (¹J_CF = 245.2 Hz), 156.1, 148.8, 148.3, 131.7, 129.2, 127.3, 125.5, 125.0, 120.3, 118.4 (²J_CF = 23.0 Hz), 109.5, 101.4 (²J_CF = 22.5 Hz), 75.7, 65.4, 61.7, 47.4, 43.4, 39.6, 36.6, 33.3, 32.4, 32.0, 31.6, 30.2, 27.4, 24.4, 21.9, 15.2 ppm. MS (ESI) m/z (%) 634.2 ([M + H]⁺, 100%). HRMS (ESI) calcd for C₃₃H₃₈FNO₈K [M + H]⁺ 634.2218, found 634.2229.

Potassium 4-(((1R,2R,4aR,5R,8aS)-2-(3-carboxypropanoyloxy)-5-((E)-2-(4-chloroquinolin-2-yl)vinyl)-1,4a-dimethyl-6-methylenedecahydronaphthalen-1-yl)methoxy)-4-oxobutanoate 9e: off white solid, 1.55 g, yield 59.85%, purity 96.3%. IR (KBr) ν_max 3419, 3085, 2933, 2856, 1759, 1725, 1631, 1572, 1443, 1389, 1341, 1273, 1234, 1112, 1036, 973, 892 cm⁻¹. ¹H NMR (600 MHz, D₂O) δ 8.64–8.55 (1H, m, 5′-H), 8.12–7.74 (3H, m, 6′,7′,8′-H), 7.54 (1H, s, 3′-H), 6.65 (1H, dd, J = 6.2 Hz, J = 15.4 Hz, 11-H), 6.56 (1H, d, J = 15.4 Hz, 12-H), 5.04 (1H, s, 13-Ha), 4.86 (1H, s, 13-Hb), 4.16 (1H, d, J = 11.8 Hz, 15-Ha), 4.01–3.95 (1H, m, 3-H), 3.83 (1H, d, J = 11.8 Hz, 15-Hb), 2.82–2.75 (9H, m, 9,18,19,22,23-H), 2.13–1.45 (9H, m, 1,2,5,6,7-H), 1.03 (3H, s, 14-H), 0.89 (3H, s, 16-H). ¹³C NMR (100 MHz, D₂O) δ 176.5, 176.1, 173.5, 173.1, 156.4, 148.8, 148.1, 136.5, 130.5, 128.8, 128.0, 126.9, 126.0, 125.8, 125.1, 118.5, 110.1, 75.5, 65.8, 61.9, 47.4, 43.3, 39.9, 36.7, 33.3, 32.6, 32.3, 32.0, 30.2, 27.9, 24.7, 21.9, 15.0 ppm. MS (ESI) m/z (%) 650.2 ([M + H]⁺, C₃₃H₃₈³⁵ClNO₈K, 100%), 652.2 ([M + H]⁺, C₃₃H₃₈³⁷ClNO₈K, 33%). HRMS (ESI) calcd for C₃₃H₃₈³⁵ClNO₈K [M + H]⁺ 650.1970, found 650.1978; for C₃₃H₃₈³⁷ClNO₈K [M + H]⁺ 652.1941, found 652.1951.

Potassium 4-(((1R,2R,4aR,5R,8aS)-2-(3-carboxypropanoyloxy)-5-((E)-2-(4-hydroxyquinolin-2-yl)vinyl)-1,4a-dimethyl-6-methylenedecahydronaphthalen-1-yl)methoxy)-4-oxobutanoate 9f: creamy white solid, 1.36 g, yield 54.18%, purity 95.8%. IR (KBr) ν_max  3478, 3392, 3082, 2948, 2854, 1756, 1723, 1638, 1572, 1442, 1386, 1342, 1272, 1232, 1116, 1034, 976, 893 cm⁻¹. ¹H NMR (600 MHz, D₂O) δ 8.33–7.80 (3H, m, 5′,7′,8′-H), 7.72–7.54 (1H, m, 6′-H), 6.83 (1H, s, 3′-H), 6.64 (1H, dd, J = 6.2 Hz, J = 15.4 Hz, 11-H), 6.53 (1H, d, J = 15.4 Hz, 12-H), 5.34 (1H, brs, 4′-OH), 5.04 (1H, s, 13-Ha), 4.85 (1H, s, 13-Hb), 4.16 (1H, d, J = 11.8 Hz, 15-Ha), 4.03–3.95 (1H, m, 3-H), 3.85 (1H, d, J = 11.8 Hz, 15-Hb), 2.82–2.73 (9H, m, 9,18,19,22,23-H), 2.16–1.42 (9H, m, 1,2,5,6,7-H), 1.04 (3H, s, 14-H), 0.85 (3H, s, 16-H). ¹³C NMR (100 MHz, D₂O) δ 176.6, 176.2, 173.7, 173.2, 166.8, 157.5, 149.1, 148.8, 130.3, 128.8, 127.2, 125.7, 125.1, 121.6, 117.6, 109.3, 102.6, 75.8, 65.6, 61.6, 47.4, 43.6, 39.7, 36.8, 33.3, 32.7, 32.3, 32.0, 30.6, 27.4, 24.4, 20.6, 15.4 ppm. MS (ESI) m/z (%) 632.2 ([M + H]⁺, 100%). HRMS (ESI) calcd for C₃₃H₃₉NO₉K [M + H]⁺ 632.2310, found 632.2320.

Potassium 4-(((1R,2R,4aR,5R,8aS)-2-(3-carboxypropanoyloxy)-1,4a-dimethyl-6-methylene-5-((E)-2-(6-methylquinolin-2-yl)vinyl)decahydronaphthalen-1-yl)methoxy)-4-oxobutanoate 9g: white solid, 1.60 g, yield 64.05%, purity 96.6%. IR (KBr) ν_max 3432, 3084, 2932, 2854, 1752, 1725, 1632, 1572, 1441, 1385, 1342, 1274, 1237, 1117, 1033, 973, 892 cm⁻¹. ¹H NMR (600 MHz, D₂O) δ 8.23 (1H, d, J = 8.3 Hz, 4′-H), 7.96 (1H, d, J = 8.3 Hz, 8′-H) 7.62–7.53 (2H, m, 5′,7′-H), 7.14 (1H, dd, J = 8.3 Hz, J = 4.3 Hz, 3′-H), 6.68 (1H, dd, J = 6.2 Hz, J = 15.4 Hz, 11-H), 6.58 (1H, d, J = 15.4 Hz, 12-H), 5.04 (1H, s, 13-Ha), 4.85 (1H, s, 13-Hb), 4.16 (1H, d, J = 11.8 Hz, 15-Ha), 4.01–3.96 (1H, m, 3-H), 3.85 (1H, d, J = 11.8 Hz, 15-Hb), 2.84–2.75 (9H, m, 9,18,19,22,23-H), 2.35 (3H, s, 6′-CH₃), 2.15–1.45 (9H, m, 1,2,5,6,7-H), 1.05 (3H, s, 14-H), 0.96 (3H, s, 16-H). ¹³C NMR (100 MHz, D₂O) δ 176.7, 176.1, 173.5, 173.0, 155.3, 148.8, 146.4, 137.3, 135.5, 130.5, 128.6, 126.4, 126.2, 125.6, 125.2, 118.7, 109.1, 75.7, 65.5, 61.6, 47.6, 43.3, 39.6, 36.5, 33.4, 32.6, 32.3, 31.6, 30.2, 27.5, 24.6, 21.5, 20.4, 15.3 ppm. MS (ESI) m/z (%) 630.2 ([M + H]⁺, 100%). HRMS (ESI) calcd for C₃₄H₄₁NO₈K [M + H]⁺ 630.2469, found 630.2482.

Potassium 4-(((1R,2R,4aR,5R,8aS)-2-(3-carboxypropanoyloxy)-5-((E)-2-(6-methoxyquinolin-2-yl)vinyl)-1,4a-dimethyl-6-methylenedecahydronaphthalen-1-yl)methoxy)-4-oxobutanoate 9h: white solid, 1.71 g, yield 64.04%, purity 96.2%. IR (KBr) ν_max 3432, 3080, 2938, 2823, 1754, 1723, 1646, 1574, 1447, 1384, 1346, 1273, 1235, 1116, 1037, 973, 892 cm⁻¹. ¹H NMR (600 MHz, D₂O) δ 8.20–8.16 (1H, m, 4′-H), 7.75 (1H, d, J = 8.3 Hz, 8′-H), 7.39–7.35 (2H, m, 3′,7′-H), 7.17–7.09 (1H, m, 5′-H), 6.66 (1H, dd, J = 6.2 Hz, J = 15.4 Hz, 11-H), 6.56 (1H, d, J = 15.4 Hz, 12-H), 5.03 (1H, s, 13-Ha), 4.86 (1H, s, 13-Hb), 4.15 (1H, d, J = 11.8 Hz, 15-Ha), 4.05–3.95 (1H, m, 3-H), 3.89 (3H, s, 6′-OCH₃), 3.83 (1H, d, J = 11.8 Hz, 15-Hb), 2.88–2.75 (9H, m, 9,18,19,22,23-H), 2.13–1.46 (9H, m, 1,2,5,6,7-H), 1.06 (3H, s, 14-H), 0.90 (3H, s, 16-H). ¹³C NMR (100 MHz, D₂O) δ 176.7, 176.4, 173.4, 173.1, 157.4, 154.4, 148.6, 143.1, 135.4, 130.7, 129.4, 125.5, 125.1, 122.5, 119.4, 109.3, 105.4, 75.9, 65.6, 61.7, 55.3, 47.4, 43.3, 39.4, 36.5, 33.6, 32.6, 32.4, 32.1, 30.2, 27.5, 24.7, 21.0, 15.1 ppm. MS (ESI) m/z (%) 646.2 ([M + H]⁺, 100%). HRMS (ESI) calcd for C₃₄H₄₁NO₉K [M + H]⁺ 646.2418, found 646.2432.

Potassium 4-(((1R,2R,4aR,5R,8aS)-2-(3-carboxypropanoyloxy)-5-((E)-2-(6-fluoroquinolin-2-yl)vinyl)-1,4a-dimethyl-6-methylenedecahydronaphthalen-1-yl)methoxy)-4-oxobutanoate 9i: off white solid, 1.31 g, yield 51.98%, purity 97.2%. IR (KBr) ν_max 3417, 3084, 2938, 2856, 1753, 1724, 1636, 1578, 1447, 1384, 1346, 1277, 1235, 1114, 1034, 975, 892 cm⁻¹. ¹H NMR (600 MHz, D₂O) δ 8.27–8.22 (1H, m, 4′-H), 7.96 (1H, d, J = 8.3 Hz, 8′-H), 7.39–7.37 (3H, m, 3′,5′,7′-H), 6.66 (1H, dd, J = 6.2 Hz, J = 15.4 Hz, 11-H), 6.55 (1H, d, J = 15.4 Hz, 12-H), 5.05 (1H, s, 13-Ha), 4.84 (1H, s, 13-Hb), 4.15 (1H, d, J = 11.8 Hz, 15-Ha), 4.06–3.95 (1H, m, 3-H), 3.86 (1H, d, J = 11.8 Hz, 15-Hb), 2.82–2.78 (9H, m, 9,18,19,22,23-H), 2.16–1.45 (9H, m, 1,2,5,6,7-H), 1.04 (3H, s, 14-H), 0.87 (3H, s, 16-H). ¹³C NMR (100 MHz, D₂O) δ 176.6, 176.2, 173.5, 173.2, 160.6 (¹J_CF = 244.8 Hz), 155.8, 148.6, 147.2, 145.3, 135.4, 130.2, 125.6, 125.3, 121.5 (²J_CF = 24.2 Hz), 119.3, 109.5 (²J_CF = 21.5 Hz), 109.1, 75.7, 65.4, 62.3, 47.7, 43.1, 40.3, 36.2, 33.6, 32.5, 32.3, 32.0, 30.3, 27.5, 24.3, 21.3, 14.8 ppm. MS (ESI) m/z (%) 634.2 ([M + H]⁺, 100%). HRMS (ESI) calcd for C₃₃H₃₈FNO₈K [M + H]⁺ 634.2218, found 634.2231.

Potassium 4-(((1R,2R,4aR,5R,8aS)-2-(3-carboxypropanoyloxy)-5-((E)-2-(6-chloroquinolin-2-yl)vinyl)-1,4a-dimethyl-6-methylenedecahydronaphthalen-1-yl)methoxy)-4-oxobutanoate 9j: offwhite solid, 1.47 g, yield 56.98%, purity 95.3%. IR (KBr) ν_max 3422, 3084, 2933, 2854, 1756, 1725, 1634, 1576, 1445, 1384, 1346, 1277, 1237, 1114, 1034, 973, 894 cm⁻¹. ¹H NMR (600 MHz, D₂O) δ 8.27–8.20 (1H, m, 4′-H), 8.12 (1H, d, J = 8.3 Hz, 8′-H), 7.83 (1H, d, J = 8.3 Hz, 7′-H), 7.36 (1H, d, J = 8.3 Hz, 3′-H), 7.14–7.07 (1H, m, 5′-H), 6.68 (1H, dd, J = 6.2 Hz, J = 15.4 Hz, 11-H), 6.52 (1H, d, J = 15.4 Hz, 12-H), 5.04 (1H, s, 13-Ha), 4.86 (1H, s, 13-Hb), 4.15 (1H, d, J = 11.8 Hz, 15-Ha), 4.05–3.92 (1H, m, 3-H), 3.82 (1H, d, J = 11.8 Hz, 15-Hb), 2.82–2.75 (9H, m, 9,18,19,22,23-H), 2.15–1.45 (9H, m, 1,2,5,6,7-H), 1.05 (3H, s, 14-H), 0.83 (3H, s, 16-H). ¹³C NMR (100 MHz, D₂O) δ 176.6, 176.2, 173.6, 173.2, 156.4, 148.6, 146.3, 135.4, 132.2, 131.4, 130.1, 128.7, 125.6, 125.3, 123.5, 119.2, 109.3, 75.8, 65.2, 61.7, 47.4, 43.3, 39.4, 36.1, 33.5, 32.6, 32.2, 32.0, 30.3, 27.2, 24.5, 21.2, 15.1 ppm. MS (ESI) m/z (%) 650.2 ([M + H]⁺, C₃₃H₃₈³⁵ClNO₈K, 100%), 652.2 ([M + H]⁺, C₃₃H₃₈³⁷ClNO₈K, 33%). HRMS (ESI) calcd for C₃₃H₃₈³⁵ClNO₈K [M + H]⁺ 650.1970, found 650.1978; for C₃₃H₃₈³⁷ClNO₈K [M + H]⁺ 652.1941, found 652.1951.

Potassium 4-(((1R,2R,4aR,5R,8aS)-5-((E)-2-(6-bromoquinolin-2-yl)vinyl)-2-(3-carboxypropanoyloxy)-1,4a-dimethyl-6-methylenedecahydronaphthalen-1-yl)methoxy)-4-oxobutanoate 9k: off white solid, 1.41 g, yield 52.03%, purity 96.8%. IR (KBr) ν_max 3416, 3078, 2934, 2855, 1755, 1723, 1636, 1574, 1447, 1385, 1346, 1273, 1235, 1114, 1035, 973, 886 cm⁻¹. ¹H NMR (600 MHz, D₂O) δ 8.28–8.05 (4H, m, 4′,5′,7′,8′-H), 7.46 (1H, d, J = 8.3 Hz, 3′-H), 6.63 (1H, dd, J = 6.2 Hz, J = 15.4 Hz, 11-H), 6.51 (1H, d, J = 15.4 Hz, 12-H), 5.04 (1H, s, 13-Ha), 4.86 (1H, s, 13-Hb), 4.15 (1H, d, J = 11.8 Hz, 15-Ha), 4.06–3.95 (1H, m, 3-H), 3.83 (1H, d, J = 11.8 Hz, 15-Hb), 2.87–2.74 (9H, m, 9,18,19,22,23-H), 2.16–1.45 (9H, m, 1,2,5,6,7-H), 1.06 (3H, s, 14-H), 0.94 (3H, s, 16-H). ¹³C NMR (100 MHz, D₂O) δ 176.7, 176.3, 173.6, 173.3, 156.4, 148.5, 148.1, 135.3, 133.4, 132.1, 129.7, 128.5, 125.5, 125.2, 123.4, 120.3, 109.3, 75.7, 65.3, 61.2, 48.4, 43.7, 40.6, 36.7, 33.4, 32.7, 32.5, 32.0, 30.5, 27.6, 24.4, 20.7, 15.0 ppm. MS (ESI) m/z (%) 694.1 ([M + H]⁺, C₃₃H₃₈⁷⁹BrNO₈K, 100%), 696.1 ([M + H]⁺, C₃₃H₃₈⁸¹BrNO₈K, 97%). HRMS (ESI) calcd for C₃₃H₃₈⁷⁹BrNO₈K [M + H]⁺ 694.1465, found 694.1475; for C₃₃H₃₈⁸¹BrNO₈K [M + H]⁺ 696.1408, found 696.1418.

Potassium 4-(((1R,2R,4aR,5R,8aS)-2-(3-carboxypropanoyloxy)-5-((E)-2-(6-hydroxyquinolin-2-yl)vinyl)-1,4a-dimethyl-6-methylenedecahydronaphthalen-1-yl)methoxy)-4-oxobutanoate 9l: creamy white solid, 1.36 g, yield 54.18%, purity 95.9%. IR (KBr) ν_max 3416, 3084, 2935, 2853, 1757, 1724, 1633, 1572, 1445, 1386, 1346, 1277, 1237, 1114, 1034, 973, 894 cm⁻¹. ¹H NMR (600 MHz, D₂O) δ 8.08–8.02 (1H, m, 4′-H), 7.84 (1H, d, J = 8.3 Hz, 8′-H), 7.45–7.13 (3H, m, 3′,5′,7′-H), 6.68 (1H, dd, J = 6.2 Hz, J = 15.4 Hz, 11-H), 6.55 (1H, d, J = 15.4 Hz, 12-H), 5.36 (1H, s, 6′-OH), 5.04 (1H, s, 13-Ha), 4.87 (1H, s, 13-Hb), 4.17 (1H, d, J = 11.8 Hz, 15-Ha), 4.07–3.95 (1H, m, 3-H), 3.85 (1H, d, J = 11.8 Hz, 15-Hb), 2.87–2.77 (9H, m, 9,18,19,22,23-H), 2.17–1.45 (9H, m, 1,2,5,6,7-H), 1.03 (3H, s, 14-H), 0.91 (3H, s, 16-H). ¹³C NMR (100 MHz, D₂O) δ 176.6, 176.4, 173.5, 173.3, 155.6, 154.2, 148.6, 143.2, 134.5, 130.6, 128.6, 125.6, 125.3, 125.0, 119.2, 111.4, 109.1, 75.7, 65.3, 61.5, 47.5, 43.2, 39.5, 36.5, 33.5, 32.6, 32.2, 32.0, 30.1, 27.4, 24.6, 20.3, 15.2 ppm. MS (ESI) m/z (%) 632.2 ([M + H]⁺, 100%). HRMS (ESI) calcd for C₃₃H₃₉NO₉K [M + H]⁺ 632.2310, found 632.2322.

Potassium 4-(((1R,2R,4aR,5R,8aS)-2-(3-carboxypropanoyloxy)-1,4a-dimethyl-6-methylene-5-((E)-2-(7-methylquinolin-2-yl)vinyl)decahydronaphthalen-1-yl)methoxy)-4-oxobutanoate 9m: white solid, 1.59 g, yield 63.60%, purity 97.9%. IR (KBr) ν_max 3421, 3084, 2933, 2852, 1753, 1722, 1633, 1572, 1444, 1385, 1344, 1274, 1233, 1116, 1035, 973, 892 cm⁻¹. ¹H NMR (600 MHz, D₂O) δ 8.23 (1H, d, J = 8.2 Hz, 4′-H), 7.90–7.58 (3H, m, 5′,6′,8′-H), 7.35 (1H, dd, J = 8.2 Hz, J = 4.3 Hz, 3′-H), 6.64 (1H, dd, J = 6.2 Hz, J = 15.4 Hz, 11-H), 6.52 (1H, d, J = 15.4 Hz, 12-H), 5.04 (1H, s, 13-Ha), 4.85 (1H, s, 13-Hb), 4.17 (1H, d, J = 11.8 Hz, 15-Ha), 4.04–3.95 (1H, m, 3-H), 3.83 (1H, d, J = 11.8 Hz, 15-Hb), 2.83–2.75 (9H, m, 9,18,19,22,23-H), 2.35 (3H, s, 7′-CH₃), 2.17–1.46 (9H, m, 1,2,5,6,7-H), 1.04 (3H, s, 14-H), 0.87 (3H, s, 16-H). ¹³C NMR (100 MHz, D₂O) δ 176.7, 176.1, 173.4, 173.1, 156.5, 148.7, 146.4, 139.4, 136.2, 130.5, 128.3, 127.1, 126.4, 125.6, 125.2, 117.4, 109.1, 75.5, 65.3, 62.4, 46.6, 43.4, 40.2, 36.3, 33.6, 32.6, 32.2, 32.0, 30.2, 27.3, 24.6, 21.3, 20.5, 15.1 ppm. MS (ESI) m/z (%) 630.2 ([M + H]⁺, 100%). HRMS (ESI) calcd for C₂₄H₄₁NO₈K [M + H]⁺ 630.2469, found 630.2480.

Potassium 4-(((1R,2R,4aR,5R,8aS)-2-(3-carboxypropanoyloxy)-5-((E)-2-(7-methoxyquinolin-2-yl)vinyl)-1,4a-dimethyl-6-methylenedecahydronaphthalen-1-yl)methoxy)-4-oxobutanoate 9n: creamy white solid, 1.66 g, yield 66.00%, purity 96.7%. IR (KBr) ν_max 3419, 3086, 2933, 2854, 1756, 1723, 1635, 1575, 1447, 1386, 1342, 1273, 1235, 1116, 1034, 971, 892 cm⁻¹. ¹H NMR (600 MHz, D₂O) δ 8.26 (1H, d, J = 8.2 Hz, 4′-H), 7.95–7.90 (1H, m, 5′-H), 7.38–7.26 (3H, m, 3′,6′,8′-H), 6.67 (1H, dd, J = 6.2 Hz, J = 15.4 Hz, 11-H), 6.55 (1H, d, J = 15.4 Hz, 12-H), 5.05 (1H, s, 13-Ha), 4.85 (1H, s, 13-Hb), 4.17 (1H, d, J = 11.8 Hz, 15-Ha), 4.06–3.95 (1H, m, 3-H), 3.86 (1H, s, 7′-OCH₃), 3.82 (1H, d, J = 11.8 Hz, 15-Hb), 2.88–2.75 (9H, m, 9,18,19,22,23-H), 2.16–1.45 (9H, m, 1,2,5,6,7-H), 1.04 (3H, s, 14-H), 0.93 (3H, s, 16-H). ¹³C NMR (100 MHz, D₂O) δ 176.5, 176.0, 173.2, 173.0, 156.5, 151.6, 148.3, 147.4, 136.5, 129.5, 128.7, 125.5, 125.1, 117.6, 116.5, 109.1, 107.4, 75.7, 65.4, 62.2, 55.4, 46.5, 43.3, 40.2, 36.6, 33.5, 32.7, 32.5, 32.0, 30.5, 27.4, 24.3, 20.6, 15.3 ppm. MS (ESI) m/z (%) 646.2 ([M + H]⁺, 100%). HRMS (ESI) calcd for C₃₄H₄₁NO₉K [M + H]⁺ 646.2418, found 646.2429.

Potassium 4-(((1R,2R,4aR,5R,8aS)-2-(3-carboxypropanoyloxy)-5-((E)-2-(7-fluoroquinolin-2-yl)vinyl)-1,4a-dimethyl-6-methylenedecahydronaphthalen-1-yl)methoxy)-4-oxobutanoate 9o: off white solid, 1.34 g, yield 53.17%, purity 96.7%. IR (KBr) ν_max 3432, 3084, 2938, 2854, 1753, 1725, 1633, 1575, 1444, 1384, 1346, 1275, 1235, 1114, 1036, 973, 892 cm⁻¹. ¹H NMR (600 MHz, D₂O) δ 8.25–8.12 (1H, m, 4′-H), 8.07–7.98 (1H, m, 5′-H), 7.76–7.64 (1H, m, 8′-H), 7.35 (1H, d, J = 8.3 Hz, 3′-H), 7.16–7.08 (1H, m, 6′-H), 6.63 (1H, dd, J = 6.2 Hz, J = 15.4 Hz, 11-H), 6.51 (1H, d, J = 15.4 Hz, 12-H), 5.05 (1H, s, 13-Ha), 4.86 (1H, s, 13-Hb), 4.17 (1H, d, J = 11.8 Hz, 15-Ha), 4.05–3.95 (1H, m, 3-H), 3.86 (1H, d, J = 11.8 Hz, 15-Hb), 2.86–2.75 (9H, m, 9,18,19,22,23-H), 2.15–1.45 (9H, m, 1,2,5,6,7-H), 1.04 (3H, s, 14-H), 0.91 (3H, s, 16-H). ¹³C NMR (100 MHz, D₂O) δ 176.7, 176.2, 173.5, 173.0, 163.6 (¹J_CF = 245.5 Hz), 157.2, 148.3, 147.4, 136.2, 130.3, 125.5, 125.1, 118.6, 116.3 (²J_CF = 22.2 Hz), 112.8 (²J_CF = 21.5 Hz), 109.5, 78.7, 65.4, 62.4, 47.5, 43.5, 40.4, 36.2, 33.3, 32.6, 32.3, 32.0, 30.1, 27.2, 24.5, 21.2, 20.1, 15.1 ppm. MS (ESI) m/z (%) 634.2 ([M + H]⁺, 100%). HRMS (ESI) calcd for C₃₃H₃₈FNO₈K [M + H]⁺ 634.2218, found 634.2232.

Potassium 4-(((1R,2R,4aR,5R,8aS)-2-(3-carboxypropanoyloxy)-5-((E)-2-(7-chloroquinolin-2-yl)vinyl)-1,4a-dimethyl-6-methylenedecahydronaphthalen-1-yl)methoxy)-4-oxobutanoate 9p: off white solid, 1.42 g, yield 55.04%, purity 96.1%. IR (KBr) ν_max 3432, 3083, 2934, 2853, 1755, 1721, 1633, 1572, 1444, 1384, 1346, 1275, 1235, 1116, 1034, 973, 890 cm⁻¹. ¹H NMR (600 MHz, D₂O) δ 8.26–8.13 (2H, m, 4′,5′-H), 7.90–7.62 (2H, m, 6′,8′-H), 7.34 (1H, d, J = 8.3 Hz, 3′-H), 6.67 (1H, dd, J = 6.2 Hz, J = 15.4 Hz, 11-H), 6.54 (1H, d, J = 15.4 Hz, 12-H), 5.05 (1H, s, 13-Ha), 4.85 (1H, s, 13-Hb), 4.17 (1H, d, J = 11.8 Hz, 15-Ha), 4.03–3.95 (1H, m, 3-H), 3.83 (1H, d, J = 11.8 Hz, 15-Hb), 2.84–2.75 (9H, m, 9,18,19,22,23-H), 2.13–1.45 (9H, m, 1,2,5,6,7-H), 1.03 (3H, s, 14-H), 0.91 (3H, s, 16-H). ¹³C NMR (100 MHz, D₂O) δ 177.6, 176.4, 173.5, 173.1, 157.6, 148.8, 147.2, 136.1, 135.4, 129.5, 128.4, 126.4, 125.5, 125.1, 124.8, 118.5, 109.1, 75.8, 65.5, 62.3, 47.4, 43.3, 40.0, 36.4, 33.2, 32.7, 32.4, 32.1, 30.2, 27.6, 24.2, 21.3, 15.1 ppm. MS (ESI) m/z (%) 650.2 ([M + H]⁺, C₃₃H₃₈³⁵ClNO₈K, 100%), 652.2 ([M + H]⁺, C₃₃H₃₈³⁷ClNO₈K, 33%). HRMS (ESI) calcd for C₃₃H₃₈³⁵ClNO₈K [M + H]⁺ 650.1970, found 650.1979; for C₃₃H₃₈³⁷ClNO₈K [M + H]⁺ 652.1941, found 652.1953.

Potassium 4-(((1R,2R,4aR,5R,8aS)-2-(3-carboxypropanoyloxy)-5-((E)-2-(7-hydroxyquinolin-2-yl)vinyl)-1,4a-dimethyl-6-methylenedecahydronaphthalen-1-yl)methoxy)-4-oxobutanoate 9q: white solid, 1.46 g, yield 58.17%, purity 95.7%. IR (KBr) ν_max 3421, 3083, 2934, 2855, 1756, 1723, 1636, 1575, 1444, 1384, 1346, 1274, 1235, 1114, 1033, 973, 892 cm⁻¹. ¹H NMR (600 MHz, D₂O) δ 8.26–8.15 (1H, m, 4′-H), 8.04–7.96 (1H, m, 5′-H), 7.36–7.18 (3H, m, 3′,6′,8′-H), 6.67 (1H, dd, J = 6.2 Hz, J = 15.4 Hz, 11-H), 6.55 (1H, d, J = 15.4 Hz, 12-H), 5.35 (1H, brs, 7′-OH), 5.06 (1H, s, 13-Ha), 4.86 (1H, s, 13-Hb), 4.17 (1H, d, J = 11.8 Hz, 15-Ha), 4.01–3.95 (1H, m, 3-H), 3.86 (1H, d, J = 11.8 Hz, 15-Hb), 2.84–2.75 (9H, m, 9,18,19,22,23-H), 2.15–1.43 (9H, m, 1,2,5,6,7-H), 1.03 (3H, s, 14-H), 0.91 (3H, s, 16-H). ¹³C NMR (100 MHz, D₂O) δ 176.6, 176.1, 173.7, 173.1, 158.5, 156.8, 151.5, 148.6, 136.2, 130.6, 125.5, 125.1, 123.3, 118.6, 116.4, 110.8, 109.1, 75.8, 65.5, 62.4, 47.4, 43.3, 40.3, 36.8, 33.5, 32.5, 32.3, 32.0, 30.3, 27.4, 24.7, 20.6, 15.1 ppm. MS (ESI) m/z (%) 632.2 ([M + H]⁺, 100%). HRMS (ESI) calcd for C₃₃H₃₉NO₉K [M + H]⁺ 632.2310, found 632.2324.

The anti-platelet aggregation activities of 8a and 9a–9q were assessed using SD (Sprague Dawley) male rat arterial blood in vitro. Thrombin and ADP were used to induce platelet aggregation. Vorapaxar sulfate and aspirin were selected as positive controls. Fresh arterial blood was taken from the groin of SD male rats (180–220 g per rat) with 3.8% sodium citrate as anticoagulant (9:1 by volume). Then, whole blood samples were centrifuged at 1000 rpm/min for 10 min at room temperature to give platelet-rich plasma (PRP-1). The residue continued to be centrifuged at 3000 rpm/min for 10 min at room temperature to prepare platelet-poor plasma (PPP). PPP was used as the blank control. The measurement range of the platelet aggregation apparatus was set according to the number of platelets of human blood. The number of platelets of human blood is (100–300) × 10⁹ L⁻¹, but the number of platelets of rats is (600–1000) × 10⁹ L⁻¹. In order to measure the platelet aggregation rate accurately, PPP was added to PRP to dilute the number of rat platelets to ~150 × 10⁹ L⁻¹ (PRP-2).^[50] The sample group solution (5 µL), with the target compound dissolved in normal saline (1.7 μmol/L) in advance, was added into PRP-2 (200 µL) and the mixture was incubated for 2 min, as well as positive controls. Normal saline (5 µL) was used as negative control with the procedure as above. Afterwards, adding 20 µL ADP (5 mM/L) or thrombin (0.1 U/mL) respectively induced platelet aggregation. IR was calculated with the formula IR = [1 − (SG/NC)] × 100% where SG and NC represent the platelet aggregation rates of sample group and negative control respectively.

Mouse fibroblast cells (L929) were used to evaluate the cell toxicity of target derivatives 9 with Cell Counting Kit-8 (CCK-8) assays.^[51] First, test compounds were dissolved and diluted to 10 and 100 μM/L with DMSO. Cells were added to 96-well microplates (1 × 10⁴ cell/well) and then cultivated at 37°C in a humidified atmosphere of CO₂ (5%) for 24 h. Second, test compounds were added into the cells and incubation was continued at 37°C for 48 h. Third, the medium was removed and 100 µL of fresh complete medium of RPMI-1640 was added. CCK-8 solution was added to the microplates at 10 μL per well. Last, the absorbance of the test solution was measured at 450 nm on a Bio-Tek Flx800 fluorescence microplate reader. According to the formula to calculate relative survival rate: relative survival rate (%) = {[Abs(test cells) − Abs(blank cells)]/[Abs(controlled cells) − Abs(blank cells)]} × 100% (Abs, absorbance).

Results are presented as the means ± s.e. (SEM). Data were analyzed with one-way ANOVA (SPSS software) to measure statistical significance of the differences. The level of significance was considered at P < 0.05 and P < 0.01.

The data that support this study are available in the article.

The authors declare no conflicts of interest.

This work was funded by Natural Science Foundation of Jiangxi Province grant no. 20212BAB206073 and earmarked fund for China Agriculture Research System of MOF and MARA Grant CARS-21.