61671-36-1Relevant academic research and scientific papers
A well-defined (POCOP)Rh catalyst for the coupling of aryl halides with thiols
Timpa, Samuel D.,Pell, Christopher J.,Ozerov, Oleg V.
supporting information, p. 14772 - 14779 (2015/01/16)
This article describes a well-defined pincer-Rh catalyst for C-S cross-coupling reactions. (POCOP)Rh(H)(Cl) serves as an active precatalyst for the coupling of aryl chlorides and bromides with aryl and alkyl thiols under reasonable conditions (3% mol cat., 110 °C, 2-24 h, >90% yield). For select substrates, >90% yields were obtained with catalyst loading as low as 0.1%. Key mechanistic intermediates have been isolated and fully characterized, including (POCOP)Rh(Ph)(SPh) (6a) and (POCOP)Rh(SPh2) (6b). The aryl/bis(phosphinite) (POCOP)Rh system has been shown to favor aryl thiolate reductive elimination at elevated temperatures and in some cases at room temperature, compared with the analogous diarylamido/bis(phosphine) (PNP)Rh pincer system. Concerted reductive elimination has been studied with 6a directly and in the presence of aryl bromide and aryl chloride traps. This investigation demonstrates a clear rate dependence on aryl chloride concentration during catalysis, a dependence that is absent when using aryl bromides. The rate of catalysis is dramatically reduced or brought to zero for ortho-tolyl halides, which can be traced to slower C-S coupling and slower carbon-halogen oxidative addition for ortho-substituted aryls. The influence of the sterics in the thiol component is less straightforward. The S-H oxidative addition product (POCOP)Rh(H)(SPh) (16) has been fully characterized and its reactivity has been examined, resulting in the isolation of the sodium-thiolate adduct (POCOP)Rh(NaSPh) (19). The solid-state structure of 19 shows Na interactions not only with sulfur, but also with a neighboring Rh and the chelating aryl carbon of the pincer framework. The reactivity of 16 and 19 indicates that these potential side products should not hinder catalysis.
Efficient C-S cross-coupling of thiols with aryl iodides catalyzed by Cu(OAc)2·H2O and 2,2′-biimidazole
Zong, Chenglong,Liu, Jianli,Chen, Shengyan,Zeng, Runsheng,Zou, Jianping
supporting information, p. 212 - 218 (2014/04/03)
The classical Ullmann C-S cross coupling reaction of aryl iodides with aromatic/alkyl thiols under catalysis of 15 mol% Cu(OAc)2· H2O and 15 mol% 2,2′-biimidazole works at 80°C in DMSO for 3 h to provide a variety of aryl sulfides in good to excellent yields. The classical Ullmann C-S cross coupling reaction of aryl iodides with aromatic/alkyl thiols under catalysis of 15 mol% Cu(OAc)2· H2O and 15 mol% 2,2′-biimidazole works at 80°C in DMSO for 3 h to provide a variety of aryl sulfides in good to excellent yields. Copyright
