- Aqueous sodium hypochlorite mediated chemoselective oxidation of chalcogenides to monoxides and dioxides by microwave exposure
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A solvent-free, rapid, and highly selective oxidation of sulfides, selenides, and tellurides (chalcogenides) to the corresponding monoxides (sulfoxides, selenoxides, and telluroxides) or the corresponding dioxides (sulfones, selenones, and tellurones) has been developed using aqueous sodium hypochlorite on solid supports by exposure to microwave. Chemoselectivity and quantitative yields have been attained in most cases.
- Khurana, Jitender,Nand, Bhaskara
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experimental part
p. 906 - 909
(2011/01/08)
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- Extremely Facile Ligand-Exchange and Disproportionation Reactions of Diaryl Sulfoxides, Selenoxides, and Triarylphosphine Oxides with Organolithium and Grignard Reagents
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Diaryl sulfoxides undergo unusually rapid ligand-exchange reaction upon treatment with organolithium reagents at -95 deg C.Optically pure phenyl p-tolyl sulfoxide (4b) reacted with organolithium reagents at the range from -20 to -95 deg C to give facile ligand-exchange and disproportionation products, i.e., diphenyl sulfoxide (7), recovered 4b, and di-p-tolyl sulfoxide (8) in a statistical ratio of 1:2:1 in quantitative yields, and the recovered 4b was completely racemized.This facile ligand exchange was observed in the similar reactions using only diaryl selenoxides and triarylphosphine oxides.The reactions of 18O-labeled phenyl p-tolyl sulfoxide (4c) with organolithium reagents gave products in a statistical ration without 18O scrambling, indicating that only the C-S bond cleavage took place under low temperature.It is suggested that the ligand exchange reactions occur by the nucleophilic attack by organolithium reagent at the sulfinyl sulfur atom, giving ?-sulfurane as an intermediate that collapses rapidly.These results suggest that the treatment of arylic sulfoxides, selenoxides, and phosphine oxides with strong bases should be effected with caution.
- Furukawa, Naomichi,Ogawa, Satoshi,Matsumura, Kazunori,Fujihara, Hisashi
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p. 6341 - 6348
(2007/10/02)
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