FeCl3-catalyzed synthesis of functionally diverse dibenzo[b,f]oxepines and benzo[b]oxepines via alkyne–aldehyde metathesis

Abstract

An efficient synthesis of dibenzo[b,f]oxepines and benzo[b]oxepines via FeCl₃-catalyzed alkyne–aldehyde metathesis reaction is described. Structurally diverse dibenzo[b,f]oxepines and benzo[b]oxepines have been achieved in good yields with high regio- and chemoselectivity under mild conditions. Notably, among the various catalysts such as Fe(III), Au(III), In(III), Zn(II), Ag(I) and triflic acid, the alkyne–aldehyde metathesis reaction of 2-(2′-phenylethynyl-phenyloxy)-benzaldehyde is only catalyzed by environmentally friendly and sustainable iron(III) chloride.