622-38-8Relevant articles and documents
Radical Ion Probes. 7. Behavior of a "Hypersensitive" Probe for Single Electron Transfer in Reactions Not Involving Electron Transfer
Tanko, James M.,Brammer Jr., Larry E.
, p. 5550 - 5556 (1997)
1-Methyl-5,7-di-tert-butylspiro[2.5]octa-4,7-dien-6-one (8) and 1,1-dimethyl-5,7-di-tert-butylspiro-[2.5]octa-4,7-dien-6-one (1) react with thiophenoxide ion to produce cyclopropane ring-opened products. Thermodynamic considerations effectively rule out any possibility that single electron transfer is involved in theses reactions; the process PhS- + substrate → PhS. + substrate.- is endothermic by over 50 kcal/moll Nucleophilic attack occurs both at the least- and most-hindered carbons of the cyclopropyl group, and the product ratio (R(1°/2°) from 8 and A(1°/3°) from 1, where 1°, 2°, and 3° refer to the regioisomeric phenyl sulfides formed from these substrates) is found to vary with solvent. In dipolar, aprotic solvents, nucleophilic attack occurs preferentially at the least-hindered carbon of the cyclopropyl group (A(1°/2°) and A(1°/3°) ≈ 4-5), consistent with an SN2 mechanism. In protic solvents, products arising from nucleophilic attack at the more-substituted carbon of the cyclopropyl group become increasingly important, consistent with the onset of a carbocationic (SN2(C+)) pathway. The strengths and weaknesses of 1 and 8 as probes for single electron transfer are discussed in the context of these results.
Nickel-catalyzed carbonylation of thioacetates with aryl iodides via CO insertion and C–S bond cleavage
Lu, Kui,Lv, Ming-Xiu,Mai, Wen-Peng,Sui, Hong-Da
, p. 890 - 895 (2021/07/02)
Aryl thioesters are synthesized via nickel-catalyzed carbonylation of thioacetates with aryl iodides. Alkyl thioacetates undergo coupling with carbon monoxide and aryl iodides to produce the desired aryl thioesters in moderate yields. This catalytic carbonylative coupling process provides a cost-effective and direct approach for the preparation of useful thioesters.
Discovery and application of methionine sulfoxide reductase B for preparation of (S)-sulfoxides through kinetic resolution
Wen, Yuanmei,Peng, Liaotian,Zhou, Yang,Peng, Tao,Chen, Yu,Cheng, Xiaoling,Chen, Yongzheng,Yang, Jiawei
, (2019/12/24)
Here we report a methionine sulfoxide reductase B (MsrB) enzymatic system for the preparation of (S)-sulfoxides through kinetic resolution of racemic (rac) sulfoxides. Eight MsrB homologue recombinant proteins were expressed and their activities on asymmetric reduction of rac-sulfoxides were analyzed. Among these MsrB homologue proteins, one protein from Acidovorax species showed good activity and enantioselectivity towards several aryl-alkyl sulfoxides. The (S)-sulfoxides were prepared with 93–98% enantiomeric excess through kinetic resolution at initial substrate concentration up to 50 mM. The establishment of MsrB catalytic kinetic resolution system provides a new efficient green strategy for preparation of (S)-sulfoxides.
