Pyrroles and related compounds. Part XI. Synthesis of two acetamidoethyl porphyrins and their conversion into vinyl porphyrins and chlorins

Abstract

A mono- and di-acetamidoethyl porphyrin have been prepared by a variant of the MacDonald method from acetamidoethyl pyrrolic intermediates. Hydrolysis and Hofmann degradation of the diacetamidoethyl porphyrin gave the corresponding divinyl prophyrin. Brief treatment with warm phosphoryl chloride in pyridine gave spirocyclic chlorins, which were formed by cyclisation of the phosphoryl chloride complexes of the acetamidoethyl side-chains.