Generation of Reactive Species Acyl Lithium and Its Reactions

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1. Generation and reactions of carbonyl anions, relatively unknown species, have been studied. The reaction of beta-phenyl-2-azaethenyllithium, generated from aryl isocyanides and t-BuLi, with carbon monoxide gives 3H-indole derivatives in 42-44% yields after quenching with MeI.Similarly, beta-phenyl-1-azaethenyllithium, obtainable by the addition of alkyllithium to benzonitriles, reacts with carbon monoxide and MeI to afford 1H-isoindole derivatives in 73-81% yields. A 1,4-diazabutadienyl anion gives a cyclic urea on reaction with carbon monoxide and MeI.These reactions represent novel [4+1] cyclocoupling reactions of dienyl anions with carbon monoxide via carbonyl anions as the intermediates.2. The reaction of lithiotrimethylsilyldiazomethane, generated from treatment of trimethylsilyldiazomethane with BuLi at -78ﾟC,with carbon monoxide at -78ﾟC followed by quenching with triethylsilyl trifluoromethanesulfonate (Et_3SiOTf) affords a bissilylketene in 85% yield. The reaction proceeds via a silylynolate which is formed by extrusion of N_2 from the carbonyllithium. The silylynolate act as ketenylation reagent. The silylynolate is found to react with carbon electrophiles such as oxiranes and ethyl benzalmalonate in the presence of equimolar amount of Me_3Al. The treatment of silylynolate with cyclohexene oxide gave a lactone via ring-opeming ketenylation followed by intramolecular cyclization. These reactions are first examples that silylynolate was trapped by carbon electrophiles.