Nuclear Magnetic Resonance Studies of Sulfur Compounds. II. The Substituent Effect on Geminal Coupling Constants and on Magnetic Nonequivalence of the Methylene Protons of Sulfoxides.
作者:Motohiro Nishio
DOI:10.1248/cpb.15.1669
日期:——
Nuclear magnetic resonance spectra were obtained for a number of sulfoxides, whose methylene protons are magnetically nonequivalent. The coupling constants between these protons depend on the electronic properties of the substituent adjacent to the coupling protons. The substituent effect on magnetic nonequivalence was also studied and it is demonstrated that the electronic properties of the substituent constitute an important factor responsible for the magnitude of magnetic nonequivalence.
Sodium Hypochlorite-promoted Novel Synthesis of Organic Ammonium Tribromides and Application of Phenanthroline Hydrotribromide in Chemoselective Oxidation of Organic Sulfides by Hydrogen Peroxide
作者:Madhudeepa Dey、Rupa R. Dey、Siddhartha S. Dhar
DOI:10.1246/cl.131192
日期:2014.5.5
A novel method of synthesis of organic ammonium tribromides (OATBs) is developed by using an inexpensive and eco-friendly sodium hypochlorite as oxidant for conversion of Br− to Br3−. The OATBs thus prepared include both quaternary ammonium tribromides and N-heterocyclic tribromides. A new addition to the family of OATBs is made in the form of phenanthroline hydrotribromide. The efficacy of this new tribromide as catalyst is ascertained in the oxidative transformation of organic sulfides to their corresponding sulfoxides and sulfones by hydrogen peroxide.
Herein we reported an efficient palladium-catalyzed enantioselective arylation of both alkyl and aryl sulfenate anions to deliver various chiral sulfoxides in good yields (up to 98%) with excellent enantioselectivities (up to 99% ee) by the use of our developed chiral O,P-ligands (PC-Phos). PC-Phos are easily prepared in shortsteps from inexpensive commercially available starting materials. The single-crystal
Tetrabutylammonium tribromide impregnated MCM-48 as a heterogeneous catalyst for selective oxidation of sulfides
作者:Prasanta Gogoi、Sukanya Hazarika、Pranjit Barman
DOI:10.1039/c5ra04573h
日期:——
We report here tetrabutylammoniumtribromide supported on MCM-48 as a highly efficient heterogeneous catalyst for the selective oxidation of sulfides, in ethanolic medium using hydrogen peroxide as an oxidant. The aforementioned oxidation reactions were found to proceed rapidly (20 min) and in good yield (85–99%) (17 examples). The oxidation products were characterized by 1H NMR, 13C NMR and elemental
我们在此报告了在MCM-48上负载的三丁基四溴化铵作为一种高效多相催化剂,用于在使用过氧化氢作为氧化剂的乙醇介质中选择性氧化硫化物。发现上述氧化反应进行迅速(20分钟),收率良好(85-99%)(17个实例)。氧化产物通过1 H NMR,13 C NMR和元素分析进行表征。通过TEM,XRD和BET表面积测量来分析催化性能。没有观察到底物的过氧化(通过GC分析),并且该催化剂有效地再循环了五个连续的循环,而其催化活性没有任何显着的损失。