Syntheses of furo[3,4-c]coumarins and related furyl coumarin derivatives via intramolecular Wittig reactions

A new and general strategy for highly functional furo[3,4-c]coumarins and related furyl coumarin derivatives has been developed, which is based on an extraordinarily facile intramolecular Wittig reaction, starting from α,β-unsaturated ketones, tributylphosphine, and acyl chlorides. The phosphorus ylides were proposed to be the key intermediates for constructing the crucial furan ring, leading to a wide variety of substituted furyl coumarins in one step.