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An Improved Catalyst System for Ullmann-Type Couplings between Alcohols and Aryl Halides
R. A. Altman, A. Shafir, A. Choi, P. A. Lichtor, S. L. Buchwald*
Massachusetts Institute of Technology, Cambridge, USA
21 February 2008 (online)
3,4,7,8-Tetramethyl-1,10-phenanthroline was found to increase the efficiency of Ullmann-type couplings between aryl halides and primary and secondary aliphatic, benzylic, allylic, and propargylic alcohols. Hereby, a number of sensititive functional groups, including ester, amine, and cyano functionalities, were tolerated. The necessary amount of alcohol used as coupling partner could be reduced to 1.5 equivalents using this catalyst system.