Tandem nucleophilic addition-intramolecular oxa-Michael reaction: Novel synthetic route to trifluoromethylated phthalans

The reaction of ortho-formyl cinnamates, ortho-formyl cinnamonitrile and ortho-formyl α-benzalketones with trifluoromethyltrimethylsilane in the presence of cesium fluoride results in the formation of trifluoromethylated phthalans in good yields. This approach provides a novel and facile access to the biologically important fluorine-containing phthalans.