title: Formation and aromatization of strained bicyclic pyrazolidines via tandem reaction of alkyl 2-aroyl-1-chlorocyclopropanecarboxylates with acylhydrazones.
abstract: A base-promoted reaction between alkyl 2-aroyl-1-chlorocyclopropanecarboxylates and acylhydrazones is described. In common solvents, the reactions proceed smoothly under mild conditions, providing mainly the formal substitution product , as well as a little amount of the formal [3 + 2] cycloaddition product . This strained bicyclic pyrazolidine , however, became the predominant product in DMSO. Moreover, a novel aromatization process of the fused pyrazolidine into 2,3,5-trisubstituted pyrrole has been successfully achieved in excellent yield via treatment with a HCl-pyridine system.
authors.affiliation: School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074, People's Republic of China. gongyf@mail.hust.edu.cn.
authors.forename: Zhimei
authors.initials: Z
authors.lastname: Huang
authors.forename: Junhao
authors.initials: J
authors.lastname: Hu
authors.forename: Yuefa
authors.initials: Y
authors.lastname: Gong
mesh_terms: D002264:Carboxylic Acids / Q000737:chemistry*; D003500:Cyclization; D006835:Hydrazones / Q000737:chemistry*; D011720:Pyrazoles / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D002264:Carboxylic Acids; D006835:Hydrazones; D011720:Pyrazoles