Stereoselective Synthesis of β-(Chloro)vinylsilanes Using a Regio- and (<i>E</i>)-Stereoselective Bis-Stannylation of Unsymmetrically Substituted Butadiynes: Application to the Synthesis of a Masked Triyne

A highly regio- and stereoselective bis-stannylation of unsymmetrically substituted butadiyne 3 provides bis-stannane 4. Selective lithiation of the internal tin residue effects a 1,4-retro-Brook rearrangement to afford vinylsilane 5. This was elaborated into the novel diethynylethene 1, which also functions as a masked triyne.