Total Synthesis of the Marine Alkaloid Discoipyrrole C via the MoOPH-Mediated Oxidation of a 2,3,5-Trisubstituted Pyrrole.

A total synthesis of the marine alkaloid discoipyrrole C (3) is described. In the pivotal step, the 2,3,5-trisubstituted pyrrole 19 was treated with MoOPH in the presence of MeOH, and the resulting methoxylated 1,2-dihydro-3H-pyrrol-3-one 20 subjected to reaction with potassium carbonate in MeOH then trifluoroacetic acid and H2O. This gave a mixture of target 3 and its dehydration product, and the structure of the former compound was confirmed by single-crystal X-ray analysis.