The manganese-catalyzed α-fluoroalkenylation of arenes via C–Hactivation and C–F cleavage has been described. This protocol provides a very useful method for the synthesis of monofluoroalkenes with predominant unconventional E-isomer selectivity which complements the existing strategies for the access to these molecular architectures. In addition, the selectivity of β-defluorination in the catalytic
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
Base Catalysis Enables Access to α,α-Difluoroalkylthioethers
作者:Douglas L. Orsi、Brandon J. Easley、Ashley M. Lick、Ryan A. Altman
DOI:10.1021/acs.orglett.7b00386
日期:2017.4.7
A nucleophilicaddition reaction of aryl thiols to readily available β,β-difluorostyrenes provides α,α-difluoroalkylthioethers. The reaction proceeds through an unstable anionic intermediate, prone to eliminate fluoride and generate α-fluorovinylthioethers. However, the use of base catalysis overcomes the facile β-fluoride elimination, generating α,α-difluoroalkylthioethers in excellent yields and
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 Exocyclic Trisubstituted Alkenes
<i>via</i>
Nickel‐ Catalyzed Kumada‐Type Cross‐Coupling Reaction of
<i>gem</i>
‐ Difluoroalkenes with Di‐Grignard Reagents
作者:Wenpeng Dai、Xuxue Zhang、Juan Zhang、Yingyin Lin、Song Cao
DOI:10.1002/adsc.201500889
日期:2016.1.21
A practical, nickel‐catalyzed Kumada‐type double cross‐coupling reaction of gem‐difluoroalkenes with 1,4‐ or 1,5‐di‐Grignard reagents was developed. The reaction proceeded efficiently at room temperature and a variety of cyclization products, arylmethylenecyclopentanes and arylmethylenecyclohexanes, were obtained in high to excellent yields, respectively.