The transmetalation (Sn to Li) and [1,4] anionic rearrangement of β-stannyl enolsilylethers have been achieved, providing a convenient method for synthesis of β-silyl ketones.
Ketone dilithio alpha,beta- and alpha,beta'-dianions can be generated by a tin-lithium exchange reaction of the lithium enolate of beta-tributyltin substituted ketones. A chelation-aided approach, which employs beta-dichlorobutyltin substituted ketones and n-BuLi, is also useful for the generation of ketone alpha,beta-dianions having the Z-geometry at the alkene. The generated dianions can be transformed into substituted ketones by reaction with various carbon electrophiles. (c) 2005 Elsevier Ltd. All rights reserved.