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.
tris(pentafluorophenyl)borane - 1,3-dicarbonyl compound - benzylic alcohol - alkylation - heterocycle