Reactions of carboxamides with vinylsilanes under oxidative conditions

• Oxidative carboxamidation of vinylsilanes with various carboxamides is studied. • The reaction course strongly depends on the structure of the reagents and the oxidant. • The products of haloamidation with solvent interception and halogenation are obtained. • 1,3-Oxazolines were synthesized quantitatively via intramolecular O-heterocyclization. The reactions of acetamide, benzamide and trifluoroacetamide with trimethyl(vinyl)-, triphenyl(vinyl)-, dimethyl(divinyl)- and diphenyl(divinyl)silanes in the presence of oxidants (t-BuOCl + NaI) or N-bromosuccinimide (NBS) in acetonitrile have been studied. Generally, all unsaturated silanes react with trifluoroacetamide to give the products of haloamidation, whereas with acetamide or benzamide the reaction affords mainly the products of halogenation. The formation of bromoamination product containing the MeCONH moiety in the NBS-induced reaction of trimethylvinylsilane with all studied amides clearly indicates that the reaction proceeds with the solvent (MeCN) interception rather than by the attack of the amide nucleophile. The product of bromoamidation from the NBS-promoted reaction undergoes a base-induced cyclization to the corresponding 1,3-oxazoline in quantitative yield.