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Transition state analysis of enantioselective Bronsted base catalysis by chiral cyclopropenimines.

ABSTRACT: Experimental (13)C kinetic isotope effects have been used to interrogate the rate-limiting step of the Michael addition of glycinate imines to benzyl acrylate catalyzed by a chiral 2,3-bis(dicyclohexylamino) cyclopropenimine catalyst. The reaction is found to proceed via rate-limiting carbon-carbon bond formation. The origins of enantioselectivity and a key noncovalent CH···O interaction responsible for transition state organization are identified on the basis of density functional theory calculations and probed using experimental labeling studies. The resulting high-resolution experimental picture of the enantioselectivity-determining transition state is expected to guide new catalyst design and reaction development.

SUBMITTER: Bandar JS

PROVIDER: S-EPMC4230825 | biostudies-literature | 2014 Jul

REPOSITORIES: biostudies-literature

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Transition state analysis of enantioselective Brønsted base catalysis by chiral cyclopropenimines.

Bandar Jeffrey S JS Sauer Gregory S GS Wulff William D WD Lambert Tristan H TH Vetticatt Mathew J MJ

Journal of the American Chemical Society 20140716 30

Experimental (13)C kinetic isotope effects have been used to interrogate the rate-limiting step of the Michael addition of glycinate imines to benzyl acrylate catalyzed by a chiral 2,3-bis(dicyclohexylamino) cyclopropenimine catalyst. The reaction is found to proceed via rate-limiting carbon-carbon bond formation. The origins of enantioselectivity and a key noncovalent CH···O interaction responsible for transition state organization are identified on the basis of density functional theory calcul ...[more]

PMID: 25029194

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