The use of phosphine ligands to control the regiochemistry of Pd-catalyzed hydrostannations of 1-alkynes: synthesis of (E)-1-tributylstannyl-1-alkenes.

The regiochemistry of palladium-catalyzed hydrostannations of terminal alkynes is dramatically influenced by ligand effects. Use of phosphines such as Cy3P, t-Bu2PCH2t-Bu, and t-Bu3P provides (E)-1-tributylstannyl-1-alkenes with regioselectivities up to >99:<1 for substrates where the commonly used Ph3P shows much lower regioselectivities.