作者:Cornelius Nussbaumer、Riccardo Cadalbert、Philip Kraft
DOI:10.1002/(sici)1522-2675(19990113)82:1<53::aid-hlca53>3.0.co;2-7
日期:1999.1.13
m-Mentha-3(8),6-diene (= isosylveterpinolene; 5),which has not been found in nature before, was shown by GC/MS analysis and co-injection with a synthetic sample to be present to the extent of 0.12-0.17% in black and green pepper oil. The synthetic reference 5 was prepared by deconjugation of 3-methylcyclohex-2-en-1-one (1), subsequent alkylation with lithium 2-lithio-2-methylpropanoate, and decarboxylative dehydration of the resulting hydroxycarboxylic acid 3 employing dimethylformamide dimethyl acetal. On polar GC columns, 5 was eluted between p-cymene and terpinolene, and was characterized by an MS similar to that of terpinolene, but with the fragment mit 121 (59, [M - Me](+)) being less intense than that of the molecular ion at mit 136 (67, M+). Since m-mentha-3(8),6-diene was also found to the extent of 0.24% in the headspace of ground black peppercorns, it can be considered to be of genuine natural origin, and thus is the first established example of a naturally occurring m-menthadiene.