The atom transfer radical addition of polyhaloalkanes, such as bromotrichloromethane and polyfluoroalkyl iodine, to olefins smoothly proceeds in the presence of sodium acetate as an efficient auxiliary agent in dimethoxyethane. The present transition metal-and peroxide-free methodology is applicable to a broad scope of substrates.
Geminal-dichloromethyl derivatives could be efficiently synthesized by the highly chemoselective platinum on carbon-catalyzed mono-dechlorination of trichloromethyl substrates in dimethyl-
Hydrogenases catalyze the reversible oxidation of H2. Carbon monoxide (CO) is known to be a competitive inhibitor of O2-sensitive [NiFe]-hydrogenases. Although the activities of some O2-tolerant [NiFe]-hydrogenases are unaffected by CO, the partially O2-tolerant [NiFe]-hydrogenase from Citrobacter sp. S-77 (S77-HYB) is inhibited by CO. In this work, the CO-bound state of S77-HYB was characterized by activity assays, spectroscopic techniques and X-ray crystallography. Electron paramagnetic resonance spectroscopy showed a diamagnetic Ni2+ state, and Fourier-transform infrared spectroscopy revealed the stretching vibration of the exogenous CO ligand. The crystal structure determined at 1.77 Å resolution revealed that CO binds weakly to the nickel ion in the Ni–Fe active site of S77-HYB. These results suggest a positive correlation between O2 and CO tolerance in [NiFe]-hydrogenases.
Platinum on Carbon-Catalyzed Precise Reduction Control of Trichloromethyl to Geminal-Dichloromethyl Groups. -A variety of aromatic and aliphatic α,α,α-trichloromethylcarbonyl compounds are successfully monodechlorinated. The method can be extended to trichloromethyl compounds bearing no adjacent carbonyl group. -(IMANISHI, T.; FUJIWARA, Y.; SAWAMA, Y.; MONGUCHI, Y.; SAJIKI*, H.; Adv. Synth. Catal. 354 (2012) 5, 771-776, http://dx.
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