Development and Mechanistic Investigation of the Palladium-Catalyzed Alpha-Arylation of Aldehydes and N-Arylation of Ammonia
A general method for the palladium-catalyzed coupling of ammonia with aryl halides and sulfonates was also developed. The catalyst generated from Pd[P(o-tol)3]2 and the alkylbisphophine CyPF-t-Bu is a highly active and selective catalyst for the coupling of ammonia with aryl chlorides, bromides, iodides, and sulfonates. The couplings of ammonia with this catalyst conducted with a solution of ammonia in dioxane formed primary arylamines from a variety of aryl electrophiles in high yields. Catalyst loadings as low as 0.1 mol % were sufficient for reactions of many aryl chlorides and bromides. In the presence of this catalyst, aryl sulfonates also coupled with ammonia for the first time in high yields. The utility of this method to generate amides, imides, and carbamates is illustrated by a one-pot synthesis of a small library of these carbonyl compounds from aryl bromides and chlorides, ammonia, and acid chlorides or anhydrides. Mechanistic studies showed that reactions conducted with the combination of CyPF t-Bu and Pd[P(o-tol)3]2 as catalyst occur with faster rates and higher yields than those conducted with CyPF-t-Bu and palladiun(II) as catalyst precursors.
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign