A unified photoredox-catalysis strategy for C(sp<sup>3</sup>)–H hydroxylation and amidation using hypervalent iodine
作者:Guo-Xing Li、Cristian A. Morales-Rivera、Fang Gao、Yaxin Wang、Gang He、Peng Liu、Gong Chen
DOI:10.1039/c7sc02773g
日期:——
unified photoredox-catalysis strategy for both hydroxylation and amidation of tertiary and benzylic C-H bonds. Use of hydroxyl perfluorobenziodoxole (PFBl-OH) oxidant is critical for efficient tertiary C-H functionalization, likely due to the enhanced electrophilicity of the benziodoxole radical. Benzylic methylene C-H bonds can be hydroxylated or amidated using unmodified hydroxyl benziodoxole oxidant Bl-OH
catalysis for the selective activation of otherwise unactivatedC(sp3)-H bonds, followed by their trifluoromethylthiolation, which has high potential as a late-stage functionalization tool. The generality of this method is exhibited through incorporation of the trifluoromethylthio group in a large number of C(sp3)-H bonds with high selectivity without the need for an excess of valuable substrate.
achieved in a highly selective fashion. This study represents the first example of selective activation of unactivated alkanes by bromine radicals in a catalytic and metal-free manner. Good reactivity was achieved by using a sealed microtubing reactor or by adding a proper amount of water. This highly selective C(sp3)–H functionalization protocol offers a new paradigm for the direct synthesis of valuable compounds
Novel Preparation of α,β-Unsaturated Aldehydes. Benzeneselenolate Promotes Elimination of HBr from α-Bromoacetals
作者:Andrei Vasil'ev、Lars Engman
DOI:10.1021/jo9917644
日期:2000.4.1
elimination/hydrolysis of these mixtures afforded alpha,beta-unsaturated aldehydes in 50-80% overall yields. In the case of tertiary alpha-bromoacetals, treatment with benzeneselenolate afforded only dehydrobromination products as mixtures of isomers. The presence of at least a catalytic amount of the organoselenium reagent was found to be crucial for olefin formation. A SET-mechanism, involving benzeneselenolate-induced
Metal-catalysed azidation of tertiary C–H bonds suitable for late-stage functionalization
作者:Ankit Sharma、John F. Hartwig
DOI:10.1038/nature14127
日期:2015.1.29
because they require excess substrate or directing groups, harsh reaction conditions, weak or acidic C–H bonds, or reagents containing specialized groups on the nitrogen atom. Among C–H bond amination reactions, those forming a C–N bond at a tertiary alkyl group would be particularly valuable, because this linkage is difficult to form from ketones or alcohols that might be created in a biosynthetic pathway