Af. Barrero et al., ALPHA-LONGIPINENE DERIVATIVES FROM SANTOLINA-VISCOSA - A CONFORMATIONAL-ANALYSIS OF THE CYCLOHEPTANE RING, Journal of natural products, 57(7), 1994, pp. 873-881
The aerial pare of Santolina viscosa afforded the new longipinene deri
vatives, methyl longipin-9-en-15-oate [1], methyl 14-hydroxylongipin-9
-en-15-oate [2], methyl 12-hydroxylongipin-9-en- 15-oate [3], methyl 1
4-methoxylongipin-9-en-15-oate [4], and methyl 12-methoxylongipin-9-en
-15-oate [5]. Their structures were established by 2D nmr experiments
and chemical correlations. The conformational analysis of the seven-me
mbered ring was achieved through the use of nmr techniques and molecul
ar mechanics calculations. Furthermore, a single-crystal X-ray diffrac
tion study of the p-bromobenzoyl derivative 3 established the absolute
stereochemistry of these compounds.