Homologation of halostannanes with carbenoids: a convenient and straightforward one-step access to α-functionalized organotin reagents.

A direct, single synthetic homologative transformation of halostannanes into mono- or di-substituted methyl analogues is documented. Critical for the success of the operation is the excellent nucleophilicity of carbenoid-like methyllithium reagents (LiCHXY, X, Y = halogen, OR, and CN): by simply individuating the reagents' substitution pattern, the desired functionalized fragment is delivered to the electrophile. The wide scope of the protocol is evidenced also in the case of analogous halogermanium compounds. The tandem homologation-quenching with nucleophiles and the use of α-chloroallyllithium is also discussed.