The mechanism of carbocyclic ring formation in the biosynthesis of the polyether antibiotic ICI139603 (2) was investigated by deuterium retention studies after incorporation of CD313CO2H, 13CD3CO2H, and CH3CD213CO2H using 2H n.m.r. spectroscopy, a- and b-isotopic shifts, and edited 13C n.m.r. spectroscopy.
Department of Chemistry
University of Cambridge