Reactions of Silenyl Lithium with Carbon Monoxide and 1-AdC(=O)H

The study of the structures, properties, and reactivity of doubly-bonded silicon compounds has made tremendous progress in the last decades, but many challenges remain. Recently we reported the isolation of silenyl lithium 1.^[1] Now we report its reactions with CO and 1-AdC(=O)H.

Exposure of a solution of silenyl lithium 1 in toluene to 1 atm of CO yields a violet solution of the first sila-allenolate 2 in quantitative yields (Scheme, path a). The reaction of 1 with 1-adamantanecarbaldehyde and consequent hydrolysis leads to siloxirane 3 (Scheme, path b). The structures of 2 and 3 were determined by X-ray crystallography and NMR spectroscopy. The mechanisms of formation of 2 and 3 will be discussed.