α-aminopimelic acids yield exclusively the ω-monoamide when they are subjected to amidation catalysed by the lipase B of Candida antarctica in anhydrous diisopropyl ether. These results are in contrast to the α-monoamide yielded by the equivalent L-glutamic derivatives under the same experimental conditions. These results show that the length of the side chain plays a crucial role in the regioselectivity of the