W. G. Whittingham, M. K. Ellis, P. Guerry, G. B. Henderson, B. Muller, D. A. Taylor, F. J. Leeper and A. R. Battersby
"Syntheses Relevant to Vitamin B12 Biosynthesis: The Malate Route to (-)-Ring-B Imide and Synthesis of the 2,7,20-Trimethylisobacteriochlorin"
J. Chem. Soc., Chem. Commun.,1989, 1116-1119. Full Text
An efficient enantioselective synthesis of (-)-ring-B imide (19) from R-malic acid is outlined and this product is used for synthesis, by a photochemical route, of the 2,7,20-trimethylisobacteriochlorin (3), of importance for biosynthetic research on vitamin B12.
Department of Chemistry
University of Cambridge