One-step conversion of 9-methyl to 9-formyldipyrrinones

9-Formyldipyrrinones may be prepared on a synthetically useful scale in 80- 90% yield by oxidation of 9-methyldipyrrinones with 2 equivalents of DDQ in TFA at -78 degreesC. Whereas reaction at higher temperatures allows oxidat ive coupling to predominate, forming biliverdins as the major product, at l ow temperatures and under controlled conditions verdin formation becomes on ly a minor pathway.