An efficient route to coumarin derivatives under dual catalysis, an organo- and a Lewis acid catalyst

An efficient reaction of dialkyl acetylenedicarboxylate with various o-hydroxy aromatic aldehydes under dual catalysis with piperidine and FeCl3 in refluxing toluene afforded alkyl 2-oxo-2-(2-oxo-2H-chromen-3-yl) acetates in good to excellent yield. The advantages of this reaction include the use of easily available starting materials, one-pot reaction, mild reaction conditions and operational simplicity.