DIASTEREOSELECTIVE ADDITION OF ORGANOMETALLIC REAGENTS TO CHIRAL IMINIUM IONS - SYNTHESIS OF (S)-(+)-CRYPTOSTYLINE-I

Iminium ion 2c participates in stereoselective nucleophilic addition reactions with Grignard reagents. Analysis of the products from reaction of 5-hexenylmagnesium bromide with iminium ion 2a suggests that these reactions proceed by a polar (two electron) mechanism. The utility of this chemistry is demonstrated in a stereospecific synthesis of (S)-(+)-cryptostylina I. © 1990.