LIGAND-EXCHANGE REACTION OF SULFOXIDES IN ORGANIC-SYNTHESIS - A NOVELMETHOD FOR SYNTHESIZING ACETYLENES AND ALLENES FROM CARBONYL-COMPOUNDS THROUGH SULFOXIDES HAVING A TRIFLUOROMETHANESULFONYLOXY GROUP ON THEBETA-CARBON

A novel method for synthesizing acetylenes and allenes from carbonyl c ompounds is described. Ligand exchange reaction of alkenylsulfoxides h aving a trifluoromethanesulfonyloxy group on the beta-carbon, which we re derived from alpha-alkyl beta-ketosulfoxides, with n-BuLi gave disu bstituted acetylenes in good yields. In the case of alkenylsulfoxides having both the trifluoromethanesulfonyloxy and aryl groups on the bet a-carbon, aryl acetylenes were obtained without treatment with n-BuLi. On the other hand, the enol triflates derived from alpha,alpha-dialky l beta-ketosulfoxides gave trisubstituted allenes on treatment with n- BuLi. This procedure was applied to the synthesis of chloroacetylenes, macrocyclic acetylenes and macrocyclic allenes.