Naphthalene-catalysed lithiation of N,N-diisopropylbenzamide and its methoxy derivatives

The reaction of N,N-disubstituted benzamide derivatives 1 with lithium and a catalytic amount of naphthalene (4 mol %) in the presence of carbonyl compounds (Barbier-type conditions) led to the formation of the corresponding 3,4-dihydro-4-substituted benzamides 2. The presence of a 4-tert-butyl group in the starting benzamide changed the position of the electrophilic fragment to give the 3,4-dihydro-3-substituted amide 3. When the reaction was performed with the corresponding methoxybenzamides 7, only reductive demethoxylation took place, giving (by reaction with carbonyl compounds) the corresponding substituted benzamides 8. (C) 1998 Elsevier Science Ltd. All rights reserved.