124867-93-2Relevant academic research and scientific papers
Terpenes and Terpene Derivatives, XXIX Synthesis and Olfactive Properties of (-)- and rac-Silphiperfol-5-en-3-ol and of Some Tris-nor Derivatives
Weyerstahl, Peter,Brendel, Joachim
, p. 669 - 678 (2007/10/02)
The new sesquiterpene alcohols silphiperfol-5-en-3-ol and the corresponding 7-epi compound (+)-1b, important constituents of the essential oil of Artemisia laciniata have been synthesized in 13 steps by starting from (R)-(+)-pulegone (6) in an overall yield of 8percent.The key reaction is the copper-catalyzed 1,4-Grignard addition of the iodo acetal 34 to the enone (+)-4 in the presence of TMSCl and TMEDA to give the silyl ether 38.Hydrolysis with spontaneous aldol cyclization and dehydration leads to the silphiperfolenones (+)-2a,b which are separable by flash chromatgraphy.The reduction with L-selectrideR gives the alcohols (-)-1a and (+)-1b which are identical in all physical properties with the isolated natural compound.With LiAlH4 the diastereoisomers 42a,b are formed.Olfactive evaluation of the isomers (-)-1a and (+)-1b has shown that the odor of the naturally occuring mixture of 1a,b with the descriptors woody, ambergris, slightly camphoraceous is correctly assigned. (-)-1a represents the more woody and camphoraceous, (+)-1b the more animal facette of ambergris.The odor of rac-1a,b, of the diasteroisomers 42a,b and of the ketones (+)-2a,b is also described as well as that of the tris-nor-silphiperfolene derivatives 29-31. Key Words: Artemisia laciniata / Sesquiterpene alcohols, tricyclic / Structure-odor correlation / (R)-(+)-Pulegone / 1,4-Grignard reaction
