Asymmetric Synthesis of Spirocyclic Oxindole δ-Lactams via NHC-Catalyzed Formal [2+4] Annulation of Aliphatic Aldehydes with Oxindole-Derived α,β-Unsaturated Ketimines

2019 ◽  
Vol 84 (18) ◽  
pp. 12177-12186
Author(s):  
Chonglong He ◽  
Zhanhuan Li ◽  
Jianfeng Xu ◽  
Hongjun Ren
2016 ◽  
Vol 52 (70) ◽  
pp. 10617-10620 ◽  
Author(s):  
Jun-Long Li ◽  
Kai-Chuan Yang ◽  
Yi Li ◽  
Qiang Li ◽  
Hong-Ping Zhu ◽  
...  

An unprecedented highly enantioselective amine catalyzed oxo-IEDDA reaction of cyclic enones with enolizable aldehydes including aqueous acetaldehyde has been developed.


2018 ◽  
Author(s):  
Marc Montesinos-Magraner ◽  
Matteo Costantini ◽  
Rodrigo Ramirez-Contreras ◽  
Michael E. Muratore ◽  
Magnus J. Johansson ◽  
...  

Asymmetric cyclopropane synthesis currently requires bespoke strategies, methods, substrates and reagents, even when targeting similar compounds. This limits the speed and chemical space available for discovery campaigns. Here we introduce a practical and versatile diazocompound, and we demonstrate its performance in the first unified asymmetric synthesis of functionalized cyclopropanes. We found that the redox-active leaving group in this reagent enhances the reactivity and selectivity of geminal carbene transfer. This effect enabled the asymmetric cyclopropanation of a wide range of olefins including unactivated aliphatic alkenes, enabling the 3-step total synthesis of (–)-dictyopterene A. This unified synthetic approach delivers high enantioselectivities that are independent of the stereoelectronic properties of the functional groups transferred. Our results demonstrate that orthogonally-differentiated diazocompounds are viable and advantageous equivalents of single-carbon chirons<i>.</i>


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