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Enantioselective bifunctional iminophosphorane catalyzed sulfa-Michael addition of alkyl thiols to unactivated ?-substituted-?,?-unsaturated esters.

ABSTRACT: The highly enantioselective sulfa-Michael addition of alkyl thiols to unactivated ?-substituted-?,?-unsaturated esters catalyzed by a bifunctional iminophosphorane (BIMP) organocatalyst is described. The low acidity of the alkyl thiol pro-nucleophiles is overcome by the high Brønsted basicity of the catalyst and the chiral scaffold/thiourea hydrogen-bond donor moiety provides the required enantiofacial discrimination in the addition step. The reaction is broad in scope with respect to the alkyl thiol and ?-substituent of the ?,?-unsaturated ester, affords sulfa-Michael adducts in excellent yields (up to >99%) and enantioselectivity (up to 97?:?3 er) and can operate down to 1 mol% catalyst loading.

SUBMITTER: Yang J

PROVIDER: S-EPMC5358540 | biostudies-literature | 2017 Jan

REPOSITORIES: biostudies-literature

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Enantioselective bifunctional iminophosphorane catalyzed sulfa-Michael addition of alkyl thiols to unactivated β-substituted-α,β-unsaturated esters.

Yang Jinchao J Farley Alistair J M AJM Dixon Darren J DJ

Chemical science 20160914 1

The highly enantioselective sulfa-Michael addition of alkyl thiols to unactivated β-substituted-α,β-unsaturated esters catalyzed by a bifunctional iminophosphorane (BIMP) organocatalyst is described. The low acidity of the alkyl thiol pro-nucleophiles is overcome by the high Brønsted basicity of the catalyst and the chiral scaffold/thiourea hydrogen-bond donor moiety provides the required enantiofacial discrimination in the addition step. The reaction is broad in scope with respect to the alkyl ...[more]

PMID: 28451207

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