A novel and convenient method for the preparation of 5-(diphenylmethylene)-1H-pyrrol-2(5H)-ones; synthesis and mechanistic study

An efficient, regioselective synthesis has been developed for the preparation of 5-(diphenylmethylene)-1H-pyrrol-2(5H)-ones from readily available 1H-pyrroles by sequential dibromination and selective organometallic bromine/lithium exchange followed by reaction with benzophenone. Comparison of various N-substituents was shown to demonstrate the high tolerance of the transformation to functional groups. The structures of the new products were determined by spectroscopic methods and confirmed by single-crystal X-ray diffraction measurement. In addition, theoretical study of the reaction mechanism and selective functionalization of the endocyclic double bond were also presented.