Aminoborohydrides. 11. Facile reduction of N-alkyl lactams to the corresponding amines using lithium aminoborohydrides.

[reaction: see text] Various five- and six-membered N-alkyl lactams were reduced to the corresponding cyclic amines using lithium N,N-dialkylaminoborohydrides (LAB). Most of the reductions were essentially complete after refluxing in THF for 2 h. The cyclic amine products were easily isolated after an aqueous workup in very good to excellent yields. It is possible to selectively reduce most functional groups, such as esters, in the presence of a lactam using LAB reagents.