EFFECT OF SUBSTITUENTS IN OSO4 REACTIONS OF METALLOCHLORINS REGIOSELECTIVE SYNTHESIS OF ISOBACTERIOCHLORINS AND BACTERIOCHLORINS

A first regioselective synthesis of bacteriochlorin by hydroxylation o f metallated chlorin with OsO4 is discussed. This is the first example for the preparation of metallobacteriochlorin. This methodology can a lso be used for the preparation of unsymmetrical isobacteriochlorins b y introducing electron-withdawing substituent(s) at the adjacent posit ion(s) of the reduced ring. The Zn(II) vic-dihydroxybacteriochlorin ob tained from 2-formyl-purpurin methyl ester showed long wavelength abso rption at 828 nm which seems to be associated with electronic interact ions of the substituents with the pi-system of the macrocycle. Copyrig ht (C) 1996 Elsevier Science Ltd