Crystal Structures of (3S*,4S*,5S*,6S*)-3,4-Epoxy- 1,7-dioxaspiro[5.5]undecan-5-ol, (3R*,5S*,6S*)-1,7- Dioxaspiro[5.5]undecane-3,5-diyl Diacetate and (4S*,5S*,6S*)-1,7-Dioxaspiro[5.5]undecane-4,5-diol

Abstract

The structures of (3S*,4S*,5S*,6S*)-3,4-epoxy-1,7-dioxaspiro[5.5]undecan-5-ol (2), (3R*,5S*,6S*)-1,7- dioxaspiro[5.5]undecane-3,5-diyl diacetate (4) and (4S*,5S*,6S*)-1,7-dioxaspiro[5.5]undecane-4,5-diol (5) have been determined by X-ray crystallography. The unsubstituted tetrahydropyran ring in (2) adopts an axial position with respect to the epoxy-substituted ring and the hydroxy group at C5 is syn to the epoxide group. Intermolecular hydrogen bonding is observed between the C5 hydroxy group and O1. The two six-membered rings in (4) adopt chair conformations and the two acetate groups adopt 1,3-diaxial positions. The C5 hydroxy group in (5) assumes an axial position anti to the C-O bond of the neighbouring ring whilst 4-OH occupies an equatorial position. Intermolecular hydrogen bonding is also observed between 4-OH and 5-OH. Compound (2), C₉H₁₄O₄, M 186·21, crystallized in the monoclinic space group P 2₁/c with a 7·867(1), b 12·2060(9), c 9·3676(8) Å, b 102·744(8), V 877·4(1) Å ³ and N_o 1163 [I > 2·5s (I)], R 0·031, Rw 0·035. Compound (4), C₁₃H₂₀O₆, M 272·30, crystallized in the triclinic space group P 1 with a 9·902(1), b 11·0024(9), c 6·9183(5)Å, a 104·078(8), b 96·769(9), g 101·980(8), V 703·8(1) Å ³ , N_o 1657 [I > 2·5s(I)], R 0·047, Rw 0·044. Compound (5), C₉H₁₆O₄, M 188·22, crystallized in the orthorhombic space group Pbca with a 25·504(3), b 8·909(2), c 8·038(2) Å, V 1826·4(5) QA 3 , N_o 1096 [I > 2·5s(I)], R 0·030, Rw 0·030.