The synthesis of pyrrole derivatives labelled with 13C in selected positions: Improved procedures

Abstract

AbstractStarting from sodium acetate‐1‐13C or ‐2‐13C improved procedures for the preparation of ethyl acetoacetate‐2,4‐13C2, ethyl acetoacetate‐1,3‐13C2, ethyl acetoacetate‐2‐13C, and ethyl acetoacetate‐2,3‐13C2 are described. A method was also worked out which allows, using the labelled ethyl acetoacetates, to obtain Knorr's pyrrole (diethyl 3,5‐dimethyl pyrrole‐2,4‐dicarboxylate) carrying the label in well‐defined positions in excellent yields. An example is given of further transformation of Knorr's pyrrole.