title: Enantioselective formal [3+3] cycloadditions of ketones and cyclic 1-azadienes by cascade enamine-enamine catalysis.
abstract: An asymmetric formal [3+3] cycloaddition process with diversely structured aliphatic ketones and electron-deficient cyclic 1-azadienes was developed by cascade enamine-enamine catalysis of a cinchona-based primary amine. This sequence involved a domino Michael addition-Mannich reaction to afford spirocyclic architectures in excellent diastereo- and enantioselectivity. Importantly, high regioselectivity was realized for a number of unsymmetrical aliphatic ketone substrates.
authors.affiliation: Key Laboratory of Drug-Targeting and Drug Delivery System of the Ministry of Education, West China School of Pharmacy, Sichuan University, Chengdu 610041 (China).
authors.forename: Xiao-Long
authors.initials: XL
authors.lastname: He
authors.forename: You-Cai
authors.initials: YC
authors.lastname: Xiao
authors.forename: Wei
authors.initials: W
authors.lastname: Du
authors.forename: Ying-Chun
authors.initials: YC
authors.lastname: Chen
keywords: [3+3] cycloaddition; aminocatalysis; cascade catalysis; enantioselectivity; regioselectivity