title: Facile synthesis of chiral spirooxindole-based isotetronic acids and 5-1H-pyrrol-2-ones through cascade reactions with bifunctional organocatalysts.
abstract: Unprecedented organocatalyzed asymmetric cascade reactions have been developed for the facile synthesis of chiral spirooxindole-based isotetronic acids and 5-1H-pyrrol-2-ones.The asymmetric 1,2-addition reactions of α-ketoesters to isatins and imines by using an acid-base bifunctional 6'-OH cinchona alkaloid catalyst, followed by cyclization and enolization of the resulting adducts, gave chiral spiroisotetronic acids and 5-1H-pyrrol-2-ones, respectively, in excellent optical purities (up to 98 % ee). FT-IR analysis supported the existence of hydrogen-bonding interaction between the 6'-OH group of the cinchona catalyst and an isatin carbonyl group, an interaction that might be crucial for catalyst activity and stereocontrol.
authors.affiliation: State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian, 116023 (China).
authors.forename: Wengang
authors.initials: W
authors.lastname: Guo
authors.forename: Xu
authors.initials: X
authors.lastname: Wang
authors.forename: Boyu
authors.initials: B
authors.lastname: Zhang
authors.forename: Shuai
authors.initials: S
authors.lastname: Shen
authors.forename: Xin
authors.initials: X
authors.lastname: Zhou
authors.forename: Peng
authors.initials: P
authors.lastname: Wang
authors.forename: Yan
authors.initials: Y
authors.lastname: Liu
authors.forename: Can
authors.initials: C
authors.lastname: Li
mesh_terms: D002384:Catalysis; D003500:Cyclization; D006860:Hydrogen Bonding; D007211:Indoles / Q000737:chemistry*; D015394:Molecular Structure; D000078183:Oxindoles; D013141:Spiro Compounds / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D007211:Indoles; D000078183:Oxindoles; D013141:Spiro Compounds; C022960:2-oxindole
keywords: cascade reactions; isatins; isotetronic acids; organocatalysis; pyrrol-2-ones