Reactions of lithium silenolates with carbonyl compounds

The chemical behavior of lithium silenolates, (Me(3)Si)(2)Si=C(OLi)R (1a, R = Mes; 1b, R = t-Bu), toward carbonyl compounds was studied. Treatment of lithium silenolates la and Ib with benzaldehyde and then with chlorotriethylsilane afforded products derived from the reactions of the lithium silenolates with 2 equiv of benzaldehyde, followed by coupling of the resulting anions with chlorotriethylsilane, in good yields. Treatment of la and Ib with mesityl aldehyde under the same conditions proceeded similarly to give the respective adducts in high yields, while the reaction of la with acetophenone gave the adduct only in low yield. Similar reactions of la and Ib with mesityl methyl ketone, however, afforded no adducts but produced lithium 1-mesitylethenolate and the respective acylbis(trimethylsilyl) silanes.