Copper Catalyzed Reactions of Aryl Grignard Reagents with Aryl Arenesulfonates

Kinetics and mechanism of the C-S coupling reactions of aryl Grignard reagents with aryl arenesulfonates

“…In our synthetic investigation, we used THF:toluene (1:10) as a solvent since we observed that the yield decreases as THF: toluene ratio increases [30]. Higher yields and/or higher reaction rates were observed in a number of reactions of Grignard reagents when toluene or toluene-diethyl ether (or THF) was used instead of ethereal solvent [48,49].…”

“…We observed selective formation of C-C and C-S coupling products in the reaction of phenyllithium with 2-chloroethyl tosylate depending on the type of Cu(I) catalyst [29]. In uncatalyzed and Cu (I) catalyzed reactions of aryl Grignard reagents with phenyl tosylate, we found [30] that, aryl Grignard reagents 1 attack tosylate 2 only by S-O bond cleavage to give sulfones 3 (Scheme 2).…”

“…Commercially available bromobenzene and subtituted bromobenzenes were purified using literature procedures. Phenyl tosylate was prepared according to the published procedure and authentic sample of phenyl p-tolyl sulfone was prepared by our reported sulfone synthesis procedure [30] using phenyl magnesium bromide-phenyl tosylate coupling. Grignard reagent was prepared in THF by standard method and their concentrations were found by titration prior to use [38].…”

An insight into the C–S coupling mechanism of aryl Grignard reagents with aryl arenesulfonates

“…Sulfonates can react as C-C coupling partners in their reaction with Cu, Ni or Pd catalyzed Grignard reagents [10][11][12][13], Cu catalyzed organolithiums, Ni and Pd catalyzed organozinc reagents [14][15][16] and with diorganocuprates [17,18] (Scheme 1a). However, arenesulfonates have been reported to react as C-S coupling products in their reaction with organolithiums [19,20] and Grignard reagents [21][22][23] (Scheme 1b). Erdik and Eroglu [23] have shown that aryl Grignard reagents can react with aryl arenesulfonates only by S-O bond cleavage in their uncatalyzed and Cu catalyzed reactions with Grignard reagents.…”

“…However, arenesulfonates have been reported to react as C-S coupling products in their reaction with organolithiums [19,20] and Grignard reagents [21][22][23] (Scheme 1b). Erdik and Eroglu [23] have shown that aryl Grignard reagents can react with aryl arenesulfonates only by S-O bond cleavage in their uncatalyzed and Cu catalyzed reactions with Grignard reagents.…”