Rhodium-catalyzed Reaction of Alkynes with Hydrosilanes and n-Octyl Isocyanide: A Silylimination/1,4-Hydrosilylation Sequence Leading to β-Silylmethyl-N-silylenamines

The silylimination of alkynes with hydrosilanes and n-octyl isocyanide, and the subsequent 1,4-hydrosilylation of the resulting β-silyl-α,β-unsaturated imines, both of which are catalyzed by Rh4(CO)12, led to the production of β-silylmethyl-N-silylenamines. The reaction of aryl-substituted alkynes proceeded when an excess molar amount of hydrosilane relative to the isocyanide was added to the vessel in one portion. In the case of alkyl-substituted alkynes, it was necessary to add the hydrosilanes in portions after the initial formation of the silylimination products, which were produced by the reaction of equimolar amounts of hydrosilanes and n-octyl isocyanide. The enamines that were produced were readily hydrolyzed to afford the corresponding β-silylaldehyde derivatives.