‘Counter-intuitive’ regioselectivity, subtle steric and solvation effects in lithiation of cyclic tertiary aralkylamines
摘要:
Lithiation of a series of cyclic aralkyl tertiary amines with sec-BuLi in various solvents has been studied. There is a subtle sensitivity to steric factors and lithium coordinating solvents/additives have an adverse effect. ortho-Lithiation is observed only in the case of an eight-membered cyclic amine and the ease of benzylic lithiation with respect to nitrogen is in the surprising order gamma > beta >> alpha, delta. These observations are discussed in the context of nitrogen coordination promoted lithiation. (c) 2005 Elsevier Ltd. All rights reserved.
Ortho metalations of ring-substituted benzyldimethylamines by butyllithium and condensations with benzophenone. Nucleophilic mechanism Cyclizations to phthalans