Veticadinol

Veticadinol (1) was isolated by Chiurdoglu and Delsemme in 1961 from Congolese vetiver oil,1 but could not at first be obtained in pure form. Various groups attempted to synthesize a substance with the structure 1 that had been assigned to veticadinol, but each attempt led to mixtures of isomeric compounds. 

The synthetic sequence presented here was the first that permitted a stereoselective preparation of veticadinol (l).2... 

The alkylidene-1,3-dicarbonyl moiety is also a highly reactive enophile. Thus, the Knoevenagel adduct (223) obtained from aldehyde (222) and dimethyl malonate in the presence of piperidinium acetate, cy-clizes by treatment with Lewis acids such as FeCb on AI2O3 exclusively to the rranr-substituted cyclohexane (224 trans.cis > 99.5 0.5 Scheme 44).7 °3 The sesquiterpene veticadinol (225) has been synthesized in enantiomerically pure form by this method.Contrary to the expectation, rranr-sub-stituted cyclopentanes can also be obtained with excellent induced and noninduced dia-stereoselectivities. Similarly, aldehydes containing an allylsilane moiety can be used for a highly stereoselective formation of rran.r-l,2-disubstituted cyclopentanes and cyclohexanes by a Knoevenagel... 

In his synthesis of the cadinane-sesquiterpene veticadinol (69), Lutz Tietze employed a sequence of Knoevenagel condensation of (i )-citronellal (66) and dimethylmalonate followed by an ene reaction provide 68 with the requisite trans stereochemistry in what was to become the decalin core of veticadinol 69. ... 

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