TERTIARY CARBINAMINES BY ADDITION OF ORGANOCERIUM REAGENTS TO NITRILES AND KETIMINES

Organocerium reagents, prepared by reaction of aromatic and primary and secondary alkyllithium reagents with anhydrous cerium chloride, add to nitriles twice to give tertiary carbinamines in often excellent yields. Addition of n-BuCeCl2 to acetophenone is about 4 times faster than addition to benzonitrile. Only 1,2-diaddition is observed in the reaction of MeCeCl2 with cinnamonitrile. The species formed in the double addition of organocerium reagents to nitriles are sufficiently basic to generate a benzyne intermediate by abstraction of an aromatic proton and nucleophilic enough to undergo an intramolecular Chichibabin reaction. Reaction of N-unsubstituted ketimines or their lithium salts with organocerium reagents permits the synthesis of tertiary carbinamines with three different groups on the tertiary carbon center.