A Convenient Synthesis of Psoralen Derivatives Oxygenated in the Pyrone Ring: 4-Methoxypsoralen and 3,4-Dimethoxypsoralen (Halkendin)

Abstract

A convenient synthesis of psoralen derivatives oxygenated in the pyrone ring, viz. 5-methoxy-7H-furo[3,2-g][l]benzopyran-7-one (4-methoxypsoralen) and 5,6-dimethoxy-7H-furo[3,2-g][l]benzopyran-7-one (3,4-dimethoxypsoralen or halkendin), has been achieved by blocking the 8-position of the coumarin ring with an iodo group, Claisen migration, and subsequent cyclization.