title: Copper-catalyzed cyclization/aza-Claisen rearrangement cascade initiated by ketenimine formation: an efficient stereocontrolled synthesis of α-allyl cyclic amidines.
abstract: An efficient and convenient synthesis of α-allyl cyclic amidines has been achieved by applying a novel cascade reaction. Copper(I)-mediated in situ N-sulfonyl ketenimine formation from the reaction of a terminal alkyne with sulfonyl azide is followed by an intramolecular nucleophilic attack on the central carbon atom by an allylic tertiary amine, and then an aza-Claisen rearrangement takes place through a chair transition state to furnish the titled amidines with complete stereocontrol.
authors.affiliation: School of Pharmaceutical Engineering and Life Science, Changzhou University, First Middle Gehu Road, Changzhou, Jiangsu Province, 213164 (China). huadongxu@gmail.com.
authors.forename: Hua-Dong
authors.initials: HD
authors.lastname: Xu
authors.forename: Zhi-Hong
authors.initials: ZH
authors.lastname: Jia
authors.forename: Ke
authors.initials: K
authors.lastname: Xu
authors.forename: Mei
authors.initials: M
authors.lastname: Han
authors.forename: Sai-Nan
authors.initials: SN
authors.lastname: Jiang
authors.forename: Jing
authors.initials: J
authors.lastname: Cao
authors.forename: Jia-Cheng
authors.initials: JC
authors.lastname: Wang
authors.forename: Mei-Hua
authors.initials: MH
authors.lastname: Shen
keywords: allylic compounds; copper; cyclization; heterocycles; rearrangements