Cobalt-Catalyzed Selective Unsymmetrical Dioxidation of <i>gem</i>-Difluoroalkenes
作者:Douglas L. Orsi、Justin T. Douglas、Jacob P. Sorrentino、Ryan A. Altman
DOI:10.1021/acs.joc.0c00415
日期:2020.8.21
proceed through reactive intermediates prone to eliminate a fluorine atom and generate monofluorinated products. Taking advantage of the distinct reactivity of gem-difluoroalkenes, we present a cobalt-catalyzed regioselective unsymmetrical dioxygenation of gem-difluoroalkenes using phenols and molecular oxygen, which retains both fluorine atoms and provides β-phenoxy-β,β-difluorobenzyl alcohols. Mechanistic
which otherwise are essentially reluctant towards F‐nucleoplilic addition, now readily participate in this fluoroallylation reaction. Furthermore, this strategy provides an elegant example for the generation, as well as functionalization, of α‐CF3‐substituted benzylic radical intermediates using cheap and readily available starting materials.
Synthesis of Alkylated Monofluoroalkenes via Fe-Catalyzed Defluorinative Cross-Coupling of Donor Alkenes with <i>gem</i>-Difluoroalkenes
作者:Ling Yang、Wei-Wei Ji、E Lin、Ji-Lin Li、Wen-Xin Fan、Qingjiang Li、Honggen Wang
DOI:10.1021/acs.orglett.8b00471
日期:2018.4.6
A reductive cross-coupling of gem-difluoroalkenes with diverse unactivated and heteroatom substituted olefins through a Fe-catalyzed hydrogen atom transfer (HAT) strategy is reported. Different from the previous HAT-type olefin cross-coupling reactions, the presence of a fluorineatom in the molecule results in a stereoselective β-F cleavage, leading to a C(sp2)–C(sp3) bond formation. A wide variety
A key intermediate, difluoromethylene phosphobetaine, in the Wittig reaction of ClCF2CO2Na–Ph3P with aldehydes was synthesized and characterized, which confirmed the reaction mechanism. The decarboxylation of this stable intermediate was a convenient approach for Wittig difluroolefination. Its reactivity could be adjusted by the modification of the substituent on the phosphorus.
Rhodium(<scp>iii</scp>)-catalyzed regio- and stereoselective benzylic α-fluoroalkenylation with gem-difluorostyrenes
作者:Lingheng Kong、Bingxian Liu、Xukai Zhou、Fen Wang、Xingwei Li
DOI:10.1039/c7cc06048c
日期:——
Rhodium(III)-catalyzed mild benzylic α-fluoroalkenylation of 8-methylquinolines with gem-difluorostyrenes has been developed. This reaction occurred via C–H activation and C–F cleavage and is applicable to a wide range of substrates, leading to the synthesis of Z-alkenyl fluorides under mild and redox-neutral conditions with high regio- and stereoselectivity.