Synthesis of alkynamides through reaction of alkyl- or aryl-substituted alkynylaluminums with isocyanates.

An efficient and facile method for the preparation of alkynamides through Et3N-catalyzed alumination of alkyl- or aryl-substituted terminal alkynes with AlMe3 and sequential nucleophilic addition of in situ generated alkynylaluminums to isocyanates is described. This method has the merits of using readily available isocyanates and monosubstituted alkynes, easy access to organoaluminums, short reaction times, and high efficiency. A gram-scale synthesis of the desired alkynamide and its application to the formation of α-methylene-ß-lactams demonstrates the synthetic utility of this method.

Stereoselective Formal Hydroamidation of Si-Substituted Arylacetylenes with DIBAL-H and Isocyanates: Synthesis of (E)- and (Z)-α-Silyl-α,ß-unsaturated Amides.

An efficient and stereoselective method for the synthesis of (E)- and (Z)-α-silyl-α,ß-unsaturated amides and its synthetic applications are presented herein. The solvent-controlled hydroaluminations of Si-substituted alkynes with DIBAL-H generate diastereomerically enriched alkenylaluminum reagents that are directly reacted with isocyanates at ambient temperature to afford α-silyl-α,ß-unsaturated amides in high yields with retained stereoselectivity. In particular, this process enables the synthesis of a broad range of (E)-α-silyl-α,ß-unsaturated amides, which are the less studied isomers. The synthetic utility of this method is highlighted by its short reaction time, ease of purification, easily accessible substrates and reagents, gram-scale synthesis, and the further transformations of C-Si bonds into C-H, C-X, and C-C bonds.