Exoselective 1,3-dipolar [3 + 6] cycloaddition of azomethine ylides with 2-acylcycloheptatrienes: stereoselectivity and mechanistic insight.
A highly exo-selective 1,3-dipolar [3 + 6] cycloaddition of azomethine ylides with 2-acylcycloheptatrienes was realized with a Cu(I)/(S,R(p))-PPF-NHMe complex as the catalyst, leading to a diverse range of bridged piperidines with multiple functionalities in good yield with excellent stereoselectivity control. Theoretical calculations indicated a stepwise mechanism for this exo-selective [3 + 6] annulation, which accounts for the remarkable feature of this annulation: all of the larger substituent groups occupy the axial positions in the six-membered chairlike conformation of the piperidine ring.
†College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China.
Zhao-Lin
ZL
He
Fu Kit
FK
Sheong
†College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China.
Qing-Hua
QH
Li
Zhenyang
Z
Lin
†College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China.|‡State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Shanghai 230012, China.
Chun-Jiang
CJ
Wang