Abstract Hydrostannation of 1-stannyl-1-alkynes leads to the formation of 1, 1-and 1, 2- distannyl-1-alkenes. The former can undergo lithiation (by alkyllithium in THF) with varying degrees of stereospecificity. 1, 1-Dilithio-1-alkenes cannot be prepared by double lithiation. The strongly basic α-stannyl vinyllithiums react with carbon electrophiles, but in some cases cause enolisation or dehydrohalogenation of the substrate. They can be readily converted ...