Acylation of Pyrrole and Investigation of Direct γ-Butyrolactone Reactions

Abstract

Selective acylation of pyrrole at two different sites (C₂, C₃) utilizing entirly different methods with good yield was achieved. The pre-formed 4-oxo-4-(1H-pyrrol-2-yl)-butyric acid (1) was taken for Clemmensen reduction and the reaction remained unchanged. The selected acylation at C₃ of pyrrole was prepared the regeoselectivity of the attack depending both on choices of catalyst and on the particular acylating agent. The pre-formed 4-oxo-4-[(1-phenylsulfonyl)-3-yl]-butyric acid was reduced through Clemmensen reduction led to the preparation of 4-(1H-pyrrol-3-yl)-butyric acid. Lactonization of this acid in the presence of Na₂S₂O₈/CuCl₂ system in H₂O at different temperatures was achieved.