1,7-Cyclogermacra-1(10),4-dien-15-al, a sesquiterpene with a novel skeleton, and other sesquiterpenes from Haitian vetiver oil

A medium polar part of commercial Haitian vetiver oil was investigated, particularly with regard to carbonyl compounds. The following new natural compounds were characterized by their NMR data: 1,7-cyclogermacra-1(10),4-dien-15-al (1); 10-epi-acor-3-en-5-one (3); 10-epi-acora-3,11-dien-15-al (4); (E)-opposita-4(15),7(11)-dien-12-al (6); 13-nor-opposit-4(15)-en-11-one (8); 7-epi-cis-dracunculifoliol (ax-4(15)-en-7-ol, 11); elema-1,11-dien-15-al (2 epimers, 12a,b); 6,12-epoxyelema-1,3-diene (14); eremophila-1(10), 6-dien-12-al (2 epimers, 15a,b); 15-nor-funebran-3-one (24); 7,15-epoxyprezizaane (31); 15-nor-prezizaan-7-one (33); 12-nor-preziza-7(15)-en-2-one (35, presumable structure); prezizaan-15-al (46); cyclocopacamphan-12-al (2 epimers, 57a,b); 5,6-seco-6,7-furoeudesman-5-one (59); 11,12,13-tri-nor-cis-eudesm-5-en-7-one (61a); 11,12,13-tri-nor-cis-eudesma-5,8-dien-7-one (62); 13-nor-eudesm-5-en-11-one (2 epimers, 63a,b); and 13-nor-trans-eudesma-4(15),7-dien-11-one (67). Two oxiranes, 13-nor-4,5-epoxyeudesm-6-en-11-one (66) and 13-nor-7,8-epoxy-trans-eudesm-4(15)-en-11-one (68), which were also isolated, might be artefacts. The polar part of the oil was converted to the methyl ethers. Distillative and chromatographic separation furnished, among others, β-funebrenyl methyl ether 23′, prezizaenyl methyl ether 50′, khusimyl methyl ether 51′, and cyclocopacamphanyl methyl ethers 58a′,b′ (epimers). Thus, the existence of the new alcohols β-funebren-14-ol (23) and prezizaen-12-ol (50) was established. The formerly described configurations of the prezizaane derivatives jinkohol, jinkohol II and jinkoholic acid are formulated as the 2-epi-compounds 45, 48 and 49.