Lewis acid-promoted cyclization of heteroatom-substituted enynes

Abstract

Lewis acid-promoted cyclizations of heteroatom-substituted enynes have been examined. The reaction of enynes 3 and 7 bearing silicon substituents on an alkyne afforded the halogenated five-membered γ-lactones 4 and γ-lactams 8 as the main products. The reaction of substrates 15 and 16 having 2-phosphonoacrylate instead of malonate also gave halogenated five-membered cyclic compounds 17 and 18 as the major products. The cyclized products are highly substituted and potentially useful for further synthetic transformations.