Journal article

Palladium-catalyzed desulfitative Mizoroki-Heck couplings of sulfonyl chlorides with mono- and disubstituted olefins: Rhodium-catalyzed desulfitative heck-type reactions under phosphine- and base-free conditions

New conditions have been found for the desulfitative Mizoroki-Heck arylation and trifluoromethylation of mono- and disubustituted olefins with arenesulfonyl and trifluoromethanesulfonyl chlorides. Thus (E)1,2-disubstituted alkenes with high stereoselectivity and 1,1,2-disubstituted alkenes with 12:1 to 21:1 E/Z steroselectivity can be obtained. Herrmann's palladacycle at 0.1 mol % is sufficient to catalyze these reactions, for which electron-rich or electron-poor sulfonyl chlorides and alkenes are suitable. If phosphine- and base-free conditions are required, 1 mol % [RhCl(C2H4)(2)] catalyzes the desulfitative cross-coupling reactions. Contrary to results reported for [RUCl2 (PPh3)(2)]-catalyzed coupling reactions with sulfonyl chlorides, the palladium and rhodium desulfitative Mizoroki-Heck coupling reactions are not inhibited by radical scavenging agents. Possible sulfones arising from the sulfonylation of alkenes at 60 degrees C are not desulfitated at higher temperatures in the presence of the Pd or Rh catalysts.


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