A procedure was developed for monoarylation of sulfones with aryl halides in the presence of palladium complexes. Optimal reaction conditions were found, and the scope of application of the proposed procedure was determined. The arylation occurs only with those sulfones which are relatively strong CH acids, the corresponding monoarylated sulfones are formed in moderate to high yields. The arylation of carbanions derived from the sulfones and some other CH acids requires the presence of an additional equivalent of base. The presence of the latter is also necessary in stoichiometric reactions of carbanions with the palladium complex CF3C6H4Pd(PPh3)(2)Br; no reaction occurs in the absence of a base. A new mechanism of arylation was proposed, where the key stage is deprotonation of palladium intermediate ArPdL2CHXY which activates the reductive elimination stage.
Palladium-catalyzed arylation of sulfonyl CH-acids
作者:Alexander N Kashin、Anton V Mitin、Irina P Beletskaya、Richard Wife
DOI:10.1016/s0040-4039(02)00321-0
日期:2002.4
A method for the palladium-catalyzed monoarylation of a series of functionalized sulfones by aryl halides is described. The reaction proceeds in the presence of 2 mol%, of Pd(2)dba(3)(.)CHCl(3) (dba=dibenzylideneacetone), PPh3 and NaH as a base, only with relatively strong CH-acids and gives monoarylated products in moderate to high yields. (C) 2002 Elsevier Science Ltd. All rights reserved.
Palladium-Catalyzed Arylation of Sulfones
作者:A. V. Mitin、A. N. Kashin、I. P. Beletskaya
DOI:10.1023/b:rujo.0000044542.70121.04
日期:2004.6
A procedure was developed for monoarylation of sulfones with aryl halides in the presence of palladium complexes. Optimal reaction conditions were found, and the scope of application of the proposed procedure was determined. The arylation occurs only with those sulfones which are relatively strong CH acids, the corresponding monoarylated sulfones are formed in moderate to high yields. The arylation of carbanions derived from the sulfones and some other CH acids requires the presence of an additional equivalent of base. The presence of the latter is also necessary in stoichiometric reactions of carbanions with the palladium complex CF3C6H4Pd(PPh3)(2)Br; no reaction occurs in the absence of a base. A new mechanism of arylation was proposed, where the key stage is deprotonation of palladium intermediate ArPdL2CHXY which activates the reductive elimination stage.