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Preparation of 9α‐Fluorinated Sesquiterpenic Drimanes and Evaluation of Their Antifeedant Activities
Author(s) -
Abad Antonio,
Agulló Consuelo,
Cuñat Ana C.,
GonzálezColoma Azucena,
Pardo David
Publication year - 2010
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200901499
Subject(s) - chemistry , organic chemistry , enol , electrophile , wittig reaction , cyanohydrin , stereoselectivity , ketone , trifluoromethanesulfonate , methyl vinyl ketone , stereochemistry , catalysis
The preparation of 9α‐fluoro analogues of both natural and unnatural drimane‐type sesquiterpenes is described. Their synthesis began with the initial preparation of methyl 8‐keto‐12‐nordriman‐11‐oate from β‐ionone and entailed the electrophilic fluorination of C‐9 for the stereoselective introduction of the fluorine atom. The drimane skeleton was completed from the intermediate 9α‐fluoro‐8‐keto‐12‐nordrimane system by means of different reactions at the C‐8 ketone carbonyl group, essentially Wittig methylenation, cyanohydrin formation or palladium‐catalysed carbonylation of the corresponding enol triflate. Further manipulation of the functionalization derived from these key reactions allowed the preparation, among others, of 9α‐fluorodrimanes, which are structurally and functionally related to albicanic acid, drimenin and olepupuane. Also described are the reactivities of some of the fluorine‐containing systems prepared and a comparative study of the antifeedant activities of a selection of 9α‐fluorodrimanes and the corresponding hydrogen analogues against several insect species with different feeding ecologies ( Spodoptera littoralis , Myzus persicae and Rhopalosiphum padi ), which revealed a significant increase in the antifeedant activities of some of the fluorinated drimane analogues.