title: Discovery and application of doubly quaternized cinchona-alkaloid-based phase-transfer catalysts.
abstract: We report the discovery of novel N,N'-disubstituted cinchona alkaloids as efficient phase-transfer catalysts for the assembly of stereogenic quaternary centers. In comparison to traditional cinchona-alkaloid-based phase-transfer catalysts, these new catalysts afford substantial improvements in enantioselectivity and reaction rate for intramolecular spirocyclization reactions with catalyst loadings as low as 0.3 mol% under mild conditions.
authors: Department of Process Chemistry, Merck and Co., Inc. P.O. Box 2000, Rahway, NJ 07065 (USA). bangping_xiang@merck.com.
authors: Bangping
authors: B
authors: Xiang
authors: Kevin M
authors: KM
authors: Belyk
authors: Robert A
authors: RA
authors: Reamer
authors: Nobuyoshi
authors: N
authors: Yasuda
mesh_terms: D002384:Catalysis; D002930:Cinchona Alkaloids / Q000138:chemical synthesis* / Q000737:chemistry*; D015394:Molecular Structure; D013141:Spiro Compounds; D013237:Stereoisomerism
chemical_list: D002930:Cinchona Alkaloids; D013141:Spiro Compounds
keywords: asymmetric synthesis; enantioselectivity; organocatalysis; phase-transfer catalysis; spiro compounds