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A Cooperative Hydrogen Bond Donor–Brønsted Acid System for the Enantioselective Synthesis of Tetrahydropyrans
Author(s) -
Maskeri Mark A.,
O'Connor Matthew J.,
Jaworski Ashley A.,
Bay Anna V.,
Scheidt Karl A.
Publication year - 2018
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201811383
Subject(s) - oxocarbenium , enantioselective synthesis , chemistry , brønsted–lowry acid–base theory , carbocation , catalysis , lewis acids and bases , counterion , hydrogen bond , organocatalysis , combinatorial chemistry , desymmetrization , ion , computational chemistry , organic chemistry , molecule , nucleophile
Carbocations stabilized by adjacent oxygen atoms are useful reactive intermediates involved in fundamental chemical transformations. These oxocarbenium ions typically lack sufficient electron density to engage established chiral Brønsted or Lewis acid catalysts, presenting a major challenge to their widespread application in asymmetric catalysis. Leading methods for selectivity operate primarily through electrostatic pairing between the oxocarbenium ion and a chiral counterion. A general approach to new enantioselective transformations of oxocarbenium ions requires novel strategies that address the weak binding capabilities of these intermediates. We demonstrate herein a novel cooperative catalysis system for selective reactions with oxocarbenium ions. This new strategy has been applied to a highly selective and rapid oxa ‐Pictet–Spengler reaction and highlights a powerful combination of an achiral hydrogen bond donor with a chiral Brønsted acid.