Palladium-catalyzed 1,6- and 1,5-diyne-carbon monoxide reaction for preparation of alkylidenecyclopentenones and -butenolides

Abstract Carbonylative [2+2+1] cycloaddition of 1,6-diyne under carbon monoxide at atmospheric pressure catalyzed by Pd 2 (dba) 3 -PPh 3 -CF 3 SO 3 H presents a new approach to the formation of a bicyclo[3.3.0]octa-1,5-dien-3-one ring system. Under higher pressure the reaction of 1,6- and 1,5-diynes occurred in a different fashion via tandem insertion of carbon monoxide to yield alkylidenebutenolide.