title: Diastereodivergent and Enantioselective [4+2] Annulations of γ-Butenolides with Cyclic 1-Azadienes.
abstract: An asymmetric annulation reaction of γ-butenolides and cyclic 1-azadienes containing a 1,2-benzoisothiazole-1,1-dioxide motif has been studied, proceeding in a tandem Michael addition-aza-Michael addition sequence. Endo-type cycloadducts bearing fused tetracyclic skeletons were isolated in fair yields and with high enantioselectivity (up to >99% ee) under the catalysis of modified cinchona alkaloid (DHQD)2PHAL. Besides, exo-type diastereomers could be produced using β-isocupreidine (β-ICD) as the catalyst, though with moderate enantioselectivity.
authors.affiliation: College of Pharmacy, Third Military Medical University, Chongqing 400038, China. lichaolucy@sina.com.
authors.forename: Chao
authors.initials: C
authors.lastname: Li
authors.affiliation: College of Pharmacy, Third Military Medical University, Chongqing 400038, China. kjiang125@hotmail.com.
authors.forename: Kun
authors.initials: K
authors.lastname: Jiang
authors.affiliation: College of Pharmacy, Third Military Medical University, Chongqing 400038, China. ycchen@scu.edu.cn.|Key Laboratory of Drug-Targeting and Drug Delivery System of the Ministry of Education, West China School of Pharmacy, Sichuan University, Chengdu 610041, China. ycchen@scu.edu.cn.
authors.forename: Ying-Chun
authors.initials: YC
authors.lastname: Chen
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: C004511:butenolide; D015107:4-Butyrolactone
keywords: 1-azadienes; Brønsted base; asymmetric organocatalysis; butenolides; cinchona alkaloids; diastereodivergence