C-C bond forming by Si-C cleavage

J. Org. Chem., 61 (20), 6901 -6905

Carbon-carbon bond formation is often considered the most difficult challenge in synthetic organic chemistry, and new or improved solutions to carbon-carbon bond-forming reactions are continuously being sought. One of the most useful categories of reagents for this purpose is the organometallic carbon nucleophiles, including organolithium, organomagnesium, and organocopper compounds.¹ Unfortunately, these reagents do have limitations. Since they are extremely strong bases as well as potent nucleophiles, their use with base sensitive substrates is precluded. Organolithium and -magnesium reagents are incompatible with halo, nitro, and cyano functionalities. Finally, benzylic and allylic organometallics are notoriously difficult to generate and prone to homocoupling.¹

An alternative methodology that circumvents these limitations is the generation of stabilized carbanions or carbanoids by cleavage of silicon-carbon bonds using fluoride anion.² The most commonly used fluoride source for this purpose is tetrabutylammonium fluoride (TBAF). The superiority of tetrabutylammonium triphenyldifluorosilicate (TBAT) to TBAF as a fluoride source for nucleophilic fluorination³ is described.