Tris(pentafluorophenyl)borane-Catalyzed Alkylation of 1,3-Dicarbonyl Compounds with Benzylic Alcohols: Access to Oxygenated Heterocycles

Tris(pentafluorophenyl)borane has found to be an effective catalyst for the alkylation of 1,3-dicarbonyl compounds using benzylic alcohols as alkylating agents. Various 1,3-dicarbonyl compounds reacted cleanly with different benzylic alcohols to provide the corresponding monoalkylated products in good yield. In addition tris(pentafluorophenyl)borane efficiently promoted the C3 alkylation of 4-hydroxycoumarins. Further, several oxygenated heterocycles such as furans, 4H-chromenes, and furanocoumarins have been prepared using the described methodology as the key step.