title: 1-Hydroxybenzotriazole-Assisted, N-Heterocyclic Carbene Catalyzed β-Functionalization of Saturated Carboxylic Esters: Access to Spirooxindole Lactones.
abstract: A 1-hydroxybenzotriazole-assisted, N-heterocyclic carbene catalyzed direct β-functionalization of saturated carboxylic esters is disclosed. This formal [3 + 2] annulation reaction of carboxylic esters with isatins affords optically pure spirooxindole lactones (on gram scale) bearing two vicinal stereogenic centers. A dual role of HOBt is proposed based on controlled experiments to rationalize the enhancement of diastereoselectivity and enantioselectivity.
authors.affiliation: Department of Chemistry, Zhejiang Sci-Tech University , Hangzhou 310018, P.R. China.
authors.forename: Jianfeng
authors.initials: J
authors.lastname: Xu
authors.affiliation: Department of Chemistry, Zhejiang Sci-Tech University , Hangzhou 310018, P.R. China.
authors.forename: Shiru
authors.initials: S
authors.lastname: Yuan
authors.affiliation: Department of Chemistry, Zhejiang Sci-Tech University , Hangzhou 310018, P.R. China.
authors.forename: Maozhong
authors.initials: M
authors.lastname: Miao
authors.affiliation: Department of Chemistry, Zhejiang Sci-Tech University , Hangzhou 310018, P.R. China.
authors.forename: Zhengkai
authors.initials: Z
authors.lastname: Chen