Showing papers by "Raymond Bonnett published in 1973"

The meso-reactivity of porphyrins and related compounds. Part VI. Oxidative cleavage of the haem system. The four isomeric biliverdins of the IX series

Abstract: The oxidative cleavage of haemin in aqueous pyridine under various conditions (ascorbic acid–oxygen; hydrazine–oxygen; and ascorbic acid–hydrogen peroxide) gives four isomeric biliverdins of the IX series which have been isolated (from a much improved ascorbic acid–oxygen reaction) as their crystalline dimethyl esters. The properties of the four isomers are described. On the basis of mass and n.m.r. spectra, structures are assigned to all four isomers for the first time. A key observation in the n.m.r. spectra of these compounds is the chemical shift of the heteroaryl methyl group. The implications of these results are discussed.

Circular dichroism of some vitamin B12 derivatives

Abstract: The c.d. spectra are recorded for a series of corrinoids possessing various structural and stereochemical features in the macrocyclic ligand. The solvent dependence of the dichroism of heptamethyl esters of dicyanocobyrinic acid and dicyano-13-epicobyrinic acid is reported. Contrary to a literature report, inversion of the c.d. at low temperatures is not observed.