Synthesis and Structure of N-(Silylalkyl)amides:  Rhodium-Catalyzed Hydrosilylation of Enamides

Rh(II) acetate effectively catalyzed the hydrosilylation of enamides, N-vinylurea, and imides to give N-(silylalkyl)amide derivatives in moderate to high yields. The silyl group was selectively introduced to the carbon atom adjacent to the nitrogen atom, whereas the efficiency and regioselectivity of the Rh-catalyzed hydrosilylation of vinyl carboxylates, thiocarboxylates, ethers, and thioethers were highly affected by the substitution patterns of the substrates and reaction conditions. The reaction of N-vinylphthalimide (1f) with deuteriosilane suggests that the catalytic process involving the oxidative addition of hydrosilane and migratory insertion of the alkenyl group of 1f is reversible. The molecular structures of the N-(1-silylethyl)phthalimide 2f and N-(1-silylethyl)acetamide 2k species have been determined by X-ray analyses. The results show that there is no intramolecular interaction between the silicon atom and the oxygen atom of the carbonyl groups of 2f and 2k.