SYNTHESIS OF GALACTOPYRANOSYL SUBSTITUTED PORPHYRINS

The synthesis of several galactopyranosyl substituted porphyrins is de scribed. Starting from porphyrin carboxylic esters (1) di-O-isopropyli dene-alpha-D-galactopyranosyl substituted porphyrins 3a-3e were synthe sised by a transesterification procedure. Treatment of 3a-3e with TFA/ water leads to the formation of galactopyranosyl substituted porphyrin s 4a-4e in excellent yield. Furthermore porphyrin 3e can be synthesise d by reaction of di-O-isopropylidene-alpha-D-galactopyranosyl substitu ted benzaldehyde 7 with pyrrole. Aldehyde 7 was synthesised by a CsF c atalysed condensation reaction of -bromo-di-O-isopropylidene-alpha-D-g alactopyranose 6 with 4-formyl benzoic acid. Copyright (C) 1996 Elsevi er Science Ltd