The synthesis of 22 π-electron macrocycles. Sapphyrins and related compounds

Abstract

Rational syntheses are described of a number of new 22 π-electron macrocycles containing pyrrole, furan, and thiophen rings and one or two direct links. A further example of the sulphur extrusion process applied to macrocycle synthesis is provided. N.m.r. studies are used to show that all the macrocycles are aromatic, and they all contain intense Soret type bands in their visible spectra. The dioxasapphyrin does not form metal complexes and shows remarkable rate differences in the electrophilic deuteriation of the meso-positions.