A CONVENIENT SYNTHESIS OF PHEROMONES - (Z)-7-NONADECEN-11-ONE, (Z)-7-EICOSEN-11-ONE AND GAMMA-DODECANOLIDE

Friedel-Crafts acylation of acetylene with acid chloride (RCOCl; R = C -8, C-9) provides a key synthon, beta-chlorovinyl ketone (Ia,b) that o n cyanation, ketalization followed by hydrogenation with Pd/C and DIBA L-H reduction furnishes gamma-ketoaldehyde (Va,b). Wittig olefination of V(a,b) with n-heptyltriphenylphosphonium bromide, provides stereosl ectively (Z)-7-nonadecen-11-one (1) and (Z)-7-eicosen-11-one (2), resp ectively. The beta-ketovinyl cyanide Ila on hydrogenation and reductio n with baker's yeast gives (S)4-)-4-hyroxydodecanonitrile (VII), which on alkaline hydrolysis and subsequent acidification with HCl furnishe s (R)-(+)-gamma-n - dodecanolactone (3).