A Convenient Method for the Conversion of Hindered Carboxylic Acids to N-Methoxy-N-methyl (Weinreb) Amides
Jacqueline C. S. Woo, Erik Fenster and Gregory R. Dake*
*Department of Chemistry, 2036 Main Mall, University of British Columbia, Vancouver, B.C., Canada, V6T 1Z1, Email: gdakechem.ubc.ca
J. C. S. Woo, E. Fenster, G. R. Dake, J. Org. Chem., 2004, 69, 8984-8986.
Sterically hindered carboxylic acids can be efficiently converted to N-methoxy-N-methyl amides with 1.1 equiv of methanesulfonyl chloride, 3 equiv of triethylamine, and 1.1 equiv of N-methoxy-N-methylamine in good yields. The major byproduct in these reactions, N-methoxy-N-methylmethanesulfonamide, can be removed under vacuum for 14-24 h.
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