Reactions of Primary Amines with Organolithium Compounds

Article abstract of DOI:10.1021/jo00171a038

Primary amines react under mild conditions with an excess of an organolithium compound to form imines and α-substituted primary amines.Frequently, N-alkylamines that result from the condensation of these products are also isolated.For example, reactions of PhCH2NH2 with RLi (R = n-Bu) in refluxing hexane furnish (after hydrolysis) PhCHRNH2, PhRC=O, PhRC=NCHRPh, and R2C=O.The organic group of the primary amine can be a primary, secondary, or tertiary alkyl group.A reaction scheme is proposed that has three types of steps: (1) Mono- and dilithiation of the primary ami ne by an organolithium compound (both lithiations generally at nitrogen). (2) Elimination from the mono- or dilithiated amine of lithium hydride or (when the alkyl group is tertiary) of the elements of an organolithium compound to produce an N-lithioimine. (3) Addition of an organolithium compound to the lithioimine to produce a new dilithiated amine.The scheme rationalizes both the structures of the products and the effects of reaction conditions on product composition.Reaction of benzonitrile with an excess of n-butyllithium furnishes (after hydrolysis) di-n-butyl ketone as the major product.Since this reaction must also proceed through an N-lithioimine, formation of this product provides additional evidence for the proposed addition and elimination steps.