Enantioselective Diarylcarbene Insertion into Si–H Bonds Induced by Electronic Properties of the Carbenes
作者:Liang-Liang Yang、Declan Evans、Bin Xu、Wen-Tao Li、Mao-Lin Li、Shou-Fei Zhu、K. N. Houk、Qi-Lin Zhou
DOI:10.1021/jacs.0c04725
日期:2020.7.15
enantioselection usually depends on differences in steric interactions between prochiral substrates and a chiral catalyst. We have discovered a carbene Si-H insertion in which the enantioselectivity depends primarily on the electronic characteristics of the carbene substrate, and the log(er) values are linearly related to Hammett parameters. A new class of chiral tetraphosphate dirhodium catalysts was developed
diazocompounds was developed to give gem-difluoroolefins, which constitutes a fast practical pathway to achieve hindered gem-difluoroolefins. The cross-coupling between difluorocarbene and aryl diazoacetates proceeded smoothly in the presence of a copper source, whereas its coupling with diaryl diazomethanes occurred well under metal-free conditions. A mechanism involving a copper–difluorocarbene complex
Direct α-Monofluoroalkenylation of Heteroatomic Alkanes via a Combination of Photoredox Catalysis and Hydrogen-Atom-Transfer Catalysis
作者:Hao Tian、Qing Xia、Qiang Wang、Jianyang Dong、Yuxiu Liu、Qingmin Wang
DOI:10.1021/acs.orglett.9b01491
日期:2019.6.21
In this study, a new C(sp3)–H monofluoroalkenylation reaction involving cooperative visible-light photoredoxcatalysis and hydrogen-atom-transfer catalysis to afford products generated by selective hydrogen abstraction and radical–radical cross-coupling was described. This mild, efficient reaction shows high regioselectivity for the α-carbon atoms of amines, ethers, and thioethers and thus allows the
Oxidation of diazo compounds by triphenyl phosphite ozonide. Quenching of singlet oxygen by diazo compounds
作者:V. V. Shereshovets、N. M. Korotaeva、A. S. Vorob'ev、V. D. Komissarov、I. I. Furlei
DOI:10.1007/bf00697131
日期:1994.9
The reaction of triphenyl phosphite ozonide with various types of diazo compounds results in their oxidation, which is accomplished by singletoxygen (1O2) evolved during thermal decomposition of the ozonide. A decrease in the ionization potential of the substrate results in an increase in the overall rate constant of quenching of1O2. In the case of 9-diazofluorene, the main channel of1O2 quenching
Dehalogenative Cross-Coupling of <i>gem</i>-Difluoroalkenes with Alkyl Halides <i>via</i> a Silyl Radical–Mediated Process
作者:Hao Tian、Shaoxiang Yang、Xiaochen Wang、Wentao Xu、Yuxiu Liu、Yongqiang Li、Qingmin Wang
DOI:10.1021/acs.joc.1c01363
日期:2021.9.17
Mechanistic experiments showed that the products were generated by selective cross-coupling of aliphatic radicals with fluoroalkenyl radicals. Silyl radical-mediated halogen abstraction enabled the protocol to be used for the monofluoroalkenylation of a broad range of alkyl and heteroaryl halides. The protocol could be carried out on a gram scale and was applied to cholesterol, indicating its utility