title: Asymmetric Michael Addition Induced by (R)-tert-Butanesulfinamide and Syntheses of Chiral Pyrazolidinone Derivatives.
abstract: A highly diastereoselective Michael addition of (R)-N-tert-butanesulfinyl imidates 8 to α,β-unsaturated pyrazolidinone 3a has been developed to afford pyrazolidinones 10 possessing three contiguous stereocenters with good to excellent yield and excellent diastereoselectivity. A two-step conversion of reduction and cyclization provides the bicyclic pyrazolopiperidine 12 in a good yield. A series of pyrazolopiperidine derivatives 18 with a quaternary carbon center at C-3a are stereoselectively synthesized via alkylation or Michael addition.
authors.affiliation: Key Laboratory of Drug Targeting of Ministry of Education, West China School of Pharmacy and State Key Laboratory of Biotherapy, Sichuan University , Chengdu 610041, P. R. China.
authors.forename: Hong-Xiu
authors.initials: HX
authors.lastname: Huang
authors.affiliation: School of Pharmaceutical Sciences and Innovative Drug Research Centre, Chongqing University , Chongqing 401331, P. R. China.
authors.forename: Hui-Jing
authors.initials: HJ
authors.lastname: Wang
authors.affiliation: Key Laboratory of Drug Targeting of Ministry of Education, West China School of Pharmacy and State Key Laboratory of Biotherapy, Sichuan University , Chengdu 610041, P. R. China.
authors.forename: Ling
authors.initials: L
authors.lastname: Tan
authors.affiliation: School of Pharmaceutical Sciences and Innovative Drug Research Centre, Chongqing University , Chongqing 401331, P. R. China.
authors.forename: Shu-Qing
authors.initials: SQ
authors.lastname: Wang
authors.affiliation: School of Pharmaceutical Sciences and Innovative Drug Research Centre, Chongqing University , Chongqing 401331, P. R. China.
authors.forename: Pei
authors.initials: P
authors.lastname: Tang
authors.affiliation: Key Laboratory of Drug Targeting of Ministry of Education, West China School of Pharmacy and State Key Laboratory of Biotherapy, Sichuan University , Chengdu 610041, P. R. China.
authors.forename: Hao
authors.initials: H
authors.lastname: Song
authors.affiliation: Key Laboratory of Drug Targeting of Ministry of Education, West China School of Pharmacy and State Key Laboratory of Biotherapy, Sichuan University , Chengdu 610041, P. R. China.
authors.forename: Xiao-Yu
authors.initials: XY
authors.lastname: Liu
authors.affiliation: Key Laboratory of Drug Targeting of Ministry of Education, West China School of Pharmacy and State Key Laboratory of Biotherapy, Sichuan University , Chengdu 610041, P. R. China.
authors.forename: Dan
authors.initials: D
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Drug Targeting of Ministry of Education, West China School of Pharmacy and State Key Laboratory of Biotherapy, Sichuan University , Chengdu 610041, P. R. China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Qin