methyllithium in tetrahydrofuran; N,N,N',N',N'',N''-hexamethylphosphoric triamide the bis-Sn deriv. was treated with 1.2 equiv of MeLi at -98°C, the mixt. was then stirred for 20 min; spectral data (the kind of spectra not indicated) confirm the structure; high-resolution mass spectrometry exhibit satisfactory molecular mass detn.;

in tetrahydrofuran; N,N,N',N',N'',N''-hexamethylphosphoric triamide treatment of the corresponding (Z)-2,3-bis(trimethylstannyl)-2-alkenoate with MeLi in THF-HMPA (-98°C, 20 min);