title: Merging Chiral Brønsted Acid/Base Catalysis: An Enantioselective [4 + 2] Cycloaddition of o-Hydroxystyrenes with Azlactones.
abstract: An enantioselective [4 + 2] cycloaddition of o-hydroxylstyrenes with azlactones has been established by merging chiral Brønsted acid (chiral phosphoric acid) and base (chiral guanidine) catalysis, which constructed a biologically important dihydrocoumarin scaffold in an efficient and enantioselective style (up to 99% yield, 96:4 er). This approach has not only realized the successful application of o-hydroxylstyrenes as oxa-diene precursors in catalytic asymmetric cycloadditions but also established a new cooperative catalytic system of chiral phosphoric acid and chiral guanidine.
authors.affiliation: School of Chemistry & Chemical Engineering, and Jiangsu Key Laboratory of Green Synthetic Chemistry for Functional Materials, Jiangsu Normal University , Xuzhou, 221116, China.
authors.forename: Yu-Chen
authors.initials: YC
authors.lastname: Zhang
authors.affiliation: School of Chemistry & Chemical Engineering, and Jiangsu Key Laboratory of Green Synthetic Chemistry for Functional Materials, Jiangsu Normal University , Xuzhou, 221116, China.
authors.forename: Qiu-Ning
authors.initials: QN
authors.lastname: Zhu
authors.affiliation: School of Chemistry & Chemical Engineering, and Jiangsu Key Laboratory of Green Synthetic Chemistry for Functional Materials, Jiangsu Normal University , Xuzhou, 221116, China.
authors.forename: Xue
authors.initials: X
authors.lastname: Yang
authors.affiliation: School of Chemistry & Chemical Engineering, and Jiangsu Key Laboratory of Green Synthetic Chemistry for Functional Materials, Jiangsu Normal University , Xuzhou, 221116, China.
authors.forename: Lu-Jia
authors.initials: LJ
authors.lastname: Zhou
authors.affiliation: School of Chemistry & Chemical Engineering, and Jiangsu Key Laboratory of Green Synthetic Chemistry for Functional Materials, Jiangsu Normal University , Xuzhou, 221116, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Shi