Enantioselective Synthesis of 2,3-Dihydrofurans via Ammonium Ylides

Abstract

A chiral, ammonium ylide based access to tetrasubstituted 2,3-dihydrofurans starting from readily available benzylidene dicarbonyls and bromo acetophenones has been developed. The products are obtained in moderate to good yields with excellent diasteroselectivity and good to excellent enantioselectivity (up to 99:1 e.r.). The employed chiral amine can be recovered in near quantitative yield. The transformation can be run as a three-component one-pot reaction, generating the ammonium salt and ylide in situ. The scope of this reaction includes 17 new dihydrofurans with aromatic or heteroaromatic substituents