The use of a new class of unsymmetrical cinchona alkaloid-based, phthalazine-bridged organocatalysts enabled the highly enantioselective dichlorination of unfunctionalized alkenes. In combination with the electrophilic chlorinating agent 1,3-dichloro-5,5dimethylhydantoin (DCDMH) and triethylsilyl chloride TES-Cl as source of nucleophilic chloride, 1-aryl-2-alkyl alkenes were dichlorinated with enantioselectivities up to 94:6 er. Initial mechanistic investigations suggest that no free chlorine is formed and, by replacement of the chloride by fluoride, enantioselective chlorofluorinations of alkenes are possible.
The solvent and autocatalytic effects of the electrophilic aromatic chlorination of benzene are studied using a combined approach of static calculations and ab initio metadynamics simulations. Different possible reaction pathways are investigated and the influence of the solvents (CCl , acetonitrile and acetic acid) is thoroughly assessed. Our results show that the stability and lifetime of a charged σ-complex is increased by electrostatic stabilisation effects of the environment, which can originate from catalytic HCl, solvating effects of polar solvents (acetonitrile), or specific hydrogen bonding interactions with the solvent (acetic acid). Metadynamics simulations reveal a new chlorine addition mechanism explaining the autocatalytic effects of the reaction. The strength of combining static calculations and metadynamics simulations is highlighted, which provide complementary insight into chemical reactions in solvent.
Sulfur(VI) Fluoride Exchange (SuFEx) chemistry has emerged as a next-generation click reaction, designed to assemble functional molecules quickly and modularly. Here, we report the ex situ generation of trifluoromethanesulfonyl fluoride...
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