Synthetic studies relevant to biosynthetic research on vitamin B12. Part 12.1 Modification of the periphery of chlorins and isobacteriochlorins

Abstract

Oxochlorins and dioxoisobacteriochlorins, which can be prepared from readily synthesised porphyrins, have been used as starting materials to develop mild, efficient methods (a) for reductive removal of the oxo-functionality to yield chlorins and isobacteriochlorins and (b) for attachment of an allyl substituent at the macrocyclic carbon bearing the oxo-functionality. It has been demonstrated that the allyl group can act as a precursor of a propionate residue, a group commonly present in the natural porphinoids.