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Nucleophilic Substitution Reactions of (Alkoxymethylene)dimethylammonium Chloride
Anthony G. M. Barrett1, D. Christopher Braddock, Rachel A. James
1Department of Chemistry, Imperial College of Science, Technology and Medicine, London, U.K. SW7 2AY, and Department of Medicinal Chemistry, Glaxo Wellcome Research and Development Ltd, Stevenage, Hertfordshire, U.K. SG1 2NY.
Abstract:
The use of imidate esters as potential replacements for diethyl azodicarboxylate and triphenylphosphine in the Mitsunobu reaction is described. A series of secondary alcohols were allowed to react with (chloromethylene)dimethylammonium chloride, generated from dimethylformamide (DMF) and oxalyl chloride, to give imidate esters. Reaction of these salts with potassium benzoate or potassium phthalimide gave the products of S(N)2 substitution in excellent yields with clean inversion of stereochemistry. Optimization of reaction conditions is discussed as a means to increase the atom economy of the process by minimizing the quantity of nucleophile required.
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