title: Enantioselective synthesis of 1,2,4-triazolines catalyzed by a cinchona alkaloid-derived organocatalyst.
abstract: An enantioselective organocatalytic process for the one-step synthesis of poly-substituted 1,2,4-triazolines is reported. The heterocycle formation is believed to go through a step-wise mechanism of nucleophilic addition of an azlactone to an azodicarboxylate in the presence of an organic base catalyst, followed by a TMSCHN2 mediated heterocyclization. Both theoretical calculations and experimental evidence suggest the pre-organization of the transition state for the chirality determining step via a unique 7-membered intramolecular hydrogen bonding.
authors.affiliation: Key Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University, Shenzhen Graduate School, Shenzhen 518055, China. huangyong@pkusz.edu.cn.
authors.forename: Qian
authors.initials: Q
authors.lastname: Shao
authors.forename: Jiean
authors.initials: J
authors.lastname: Chen
authors.forename: Meihua
authors.initials: M
authors.lastname: Tu
authors.forename: David W
authors.initials: DW
authors.lastname: Piotrowski
authors.forename: Yong
authors.initials: Y
authors.lastname: Huang
mesh_terms: D002384:Catalysis; D060326:Chemistry Techniques, Synthetic; D002930:Cinchona Alkaloids / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D013237:Stereoisomerism; D013379:Substrate Specificity; D014230:Triazoles / Q000138:chemical synthesis* / Q000737:chemistry*
chemical_list: D002930:Cinchona Alkaloids; D014230:Triazoles; C013595:mercaptotriazole