R3SiMgMe and MnCl2 are disclosed. (1) The manganese species reacted with terminal acetylenes to give 1,2-disilylated 1-alkenes. Mono- and bis(trimethylsilyl) acetylenes gave tri- and tetrasilylated ethenes, respectively, in good yields. Highly strained tetrakis(trimethylsilyl) ethene has now become easily accessible by this technique. (2) The reaction of alkenyl halides, alkenyl sulfides, and enol phosphates
The reaction of alkenyl halides, alkenyl sulfides, and enol phosphates with (R3Si)3MnMgMe provides vinylsilanes in good yields. The method is also applicable to the allylsilanesynthesis from allylic sulfides and ethers.
produces tantalum-alkyne complexes (not isolated), which react in situ with phenyl isocyanate (or butyl isocyanate) to give (E)-α,β-unsaturated amides stereoselectively. The tantalum–alkyne complexes also react with acyl cyanides in the presence of BF3·OEt2 to give α-cyanohydrins. In both reactions, filtration of the reaction mixture containing the tantalum–alkyne complexes before addition of isocyanates