Conjugate, homoconjugate, and 1,2-additions of acetylene nucleophiles and their application to prostaglandin synthesis

Abstract

1-Acylcyclopent-1 -enes (10) and (11) undergo 1,4- and 1,2-addition reactions with various alkynylalane reagents at ambient temperatures. Homoconjugate additions of alkynylalanes to endo-3-t- butyldimethylsilyloxytricyclo[3.2.0.0^2,7]heptan-6-one (12) occur to give 7-anti-alkynylbicyclo[2.2.1]heptanones (24) and (25). 1-Lithioalk-1-ynes can undergo conjugate additions when the reagent is solvated with, hexamethyiphosphoric triamide. These reactions, designed to provide an approach to prostanoic acid derivatives and their intermediates, avoid the use of low temperatures for conjugate additions.