FeCl3-catalyzed dimerization/elimination of 1,1-diarylalkenes: efficient synthesis of functionalized 4H-chromenes

Abstract

An efficient synthesis of valuable poly-substituted 4H-chromenes was developed via a [4 + 2] cycloaddition followed by the elimination of 1,1-diarylalkenes. The inexpensive FeCl₃ salt has proven to be an efficient catalyst for this transformation. The commercial availability of the catalyst and reagents, together with a convenient procedure, makes this an attractive method for 4H-chromene synthesis.