
TY  - JOUR
A1  - Grant, HG 
A1  - O'Regan, PJ 
A1  - Park, RJ 
A1  - Sutherland, MD 
T1  - Terpenoid chemistry.  XXIV. (1R)-1-Methoxymyodesert-3-ene, an Iridoid Constitutent of Myoporum deserti (Myoporaceae)
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1980
VL  - 33
IS  - 4
SP  - 853
EP  - 878
KW  - 
UR  - https://doi.org/10.1071/CH9800853 
N2  - A common variety of Myoporum deserti A. Cunn. (Ellangowan Poison Bush) yields an essential oil consisting largely of the iridoid monoterpene, (1R)-1-methoxymyodesert-3-ene, C11H18O2,(1R,4aS,7R,7aR)-1-methoxy-4,7- dimethyl-1,4a,5,6,7,7a-hexahydrocycopenta[c]pyran, b.p. 67&#176;/2 mm,[&#945;]D- 165&#176;. This cyclic acetal is hydrolysed to methanol and a mixture of two epimeric cyclopentanoid dialdehydes which are oxidized to the two epimeric trans,trans-nepetalinic acids and yield (+)-(R)-actinidine with Brady's reagent. (1R)-1-Methoxymyodesert-3-ene is oxidized by ozone/hydrogen peroxide to (1R,2R,5R)-2-acetyl-5- methylcyclopentanecarboxylic acid. Hydrogenation yields mainly (1R)- methoxymyodesertan, hydrolysed by aqueous maleic acid at room temperature to methanol and a cyclic hemiacetal, (1R,4R,4aR,7R,7aR)- 4,7-dimethyl-1,3,4,4a,5,6,7,7a-octahydrocyclopenta[c]pyran-1-ol. Oxidation of this cis,cis-hemiacetal by bromine in acetate buffer yields a lactone further oxidized by chromic acid to (2R,1'S,2'R,3'R)- 2-(2'-carboxy-3'-methylcyclopentyl)-propionic acid.     (1R)-1-Methoxymyodesertan, refluxed with aqueous phthalic acid, yields (+)-(4R,4aR,7R)-4,7-dimethyl-3,4,4a,5,6,7-hexahydrocyclopenta[c]pyran. Treatment of the hexahydropenta[c]pyran, the cis,cis-hemiacetal or (1R)-1-methoxymyodesertan with hydrochloric acid yields a trans,trans-hemiacetal, (1R,4R,4aR,7R,7aS)-4,7-dimethyl- 1,3,4,4a,5,6,7,7a-octahydrocyclopenta[c]pyran-1-ol, which equilibrates in solution to a mixture of &#945;- and &#946;-anomers. Spectral studies of these and otherproducts establish the configuration of the natural product at C1.     (1R)-1-Methoxymyodesert-3-ene is not toxic to sheep as are the &#946;- substituted furans characteristic of most other chemovarieties of M. deserti. 
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