Expedient Approach to 6-Bromo-2-isopropylidenecoumaranone, a Potential Intermediate for the Synthesis of TMC-120B, Pseudodeflectusin and their Congeners

KAUFMAN, T. S.; PERGOMET, J. L.; BRACCA, A. B. J.

HELVETICA CHIMICA ACTA

WILEY-V C H VERLAG GMBH

Lugar: Weinheim; Año: 2016 vol. 99 p. 398 - 404

0018-019X

A straightforwardapproach towards 6-bromo-2-isopropylidenecoumaranone, a potential intermediatetowards alkaloid TMC 120-B, pseudodeflectusin and other natural products, isreported. The synthetic sequence involved the reaction of 3-bromosalicylaldehydewith chloroacetone and cyclization of the resulting ether to a 2-acetylcoumaranolintermediate. This was followed by sequential methyl Grignard addition and Jones?oxidation to the corresponding coumaranone, which was dehydrated to the finalproduct with the methanesulfonyl chloride/pyridine reagent. Protection of thecoumaranol as the corresponding THP-ether resulted in improved product yields.