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In 2012, the Jacobsen group demonstrated that hydrogen bonding catalysts could affect the asymmetric ring opening of episulfonium cations with indoles (Scheme 4.57) [193]. The source of the enantioselectivity was proposed to be an ensemble of electrostatic, cation‐π, and hydrogen‐bonding interactions between the anion‐bound catalyst, indole, and episulfonium. The Gouverneur lab extended this reactivity to utilizing fluoride as the nucleophile, a notoriously challenging fluorine source for asymmetric fluorination reactions [194]. Other advances in the field include an asymmetric selenocyclization through the intermediacy of a seleniranium ion‐pair [195]. It was shown that the seleniranium readily interconverts between two enantiomers via group transfer, allowing for a Curtin‐Hammett situation that determines the enantioselectivity of the reaction.