Catalyst- and Substituent-Controlled Switching of Chemoselectivity for the Enantioselective Synthesis of Fully Substituted Cyclobutane Derivatives via 2 + 2 Annulation of Vinylogous Ketone Enolates and Nitroalkene

2018 ◽  
Vol 20 (24) ◽  
pp. 7835-7839 ◽  
Author(s):  
Pavan Sudheer Akula ◽  
Bor-Cherng Hong ◽  
Gene-Hsiang Lee
Synlett ◽  
2021 ◽  
Author(s):  
Memg Wang ◽  
Changxu Zhong ◽  
Ping Lu

Enantioselective synthesis of cyclobutane derivatives is still a challenging topic in asymmetric synthesis. [2+2]-Cycloaddition and skeleton rearrangement are two primary strategies to this end. Recently, functionalization of cyclobutanones and cyclobutenones, which are readily available via [2+2]-cycloadditions as prochiral substrates, has emerged as a powerful tool to access versatile four-membered ring compounds. Herein, we summarize some recent advances in these areas from our and other groups.


2021 ◽  
Author(s):  
Aditya Chakrabarty ◽  
Santanu Mukherjee

Enantioselective allenylic alkylation reactions of unstabilized enolates have never been reported. We now present a unified fragment-coupling strategy for the first enantioselective synthesis of α-allenylic amides and ketones through allenyl-ic alkylation of vinyl azides. In these chemodivergent reactions, cooperatively catalyzed by Ir(I)/(phosphoramidite,olefin) complex and Sc(OTf)3, vinyl azides act as the surrogate for both amide enolates and ketone enolates. The desiccant (molecular sieves) plays a crucial role in controlling the chemodivergency of this enantioconvergent and regioselective reaction: Under otherwise identical reaction conditions, the presence of the desiccant led to α-allenylic amides while its absence resulted in α-allenylic ketones from the same substrate combinations. Utilizing race-mic allenylic alcohols as the alkylating agent, the overall process represents a dynamic kinetic asymmetric transformation (DyKAT), where both α-allenylic amides and ketones are formed with the same absolute configuration generally with outstanding enantioselectivity. To the best of our knowledge, this is the first example of the use of vinyl azide as the ketone enolate surrogate in an enantioselective transformation.


2016 ◽  
Vol 14 (30) ◽  
pp. 7295-7303 ◽  
Author(s):  
Wanxing Sha ◽  
Lijun Zhang ◽  
Wenzhong Zhang ◽  
Haibo Mei ◽  
Vadim A. Soloshonok ◽  
...  

The first enantioselective catalytic aldol–cyclization cascade reaction of detrifluoroacetylatively in situ generated tertiary enolates with methyl 2-formylbenzoate is reported.


Author(s):  
Xin-Ming Xu ◽  
Ming Xie ◽  
Jiazhu Li ◽  
Mei-Xiang Wang

An exquisite Pybox/Cu(OTf)2-catalyzed asymmetric tandem reaction of tertiary enamides was developed, which enabled the expeditious synthesis of indolizino[8,7-b]indole derivatives in high yield, excellent enantioselectivity and diastereoselectivity.


2018 ◽  
Author(s):  
Matthew L. Landry ◽  
Grace McKenna ◽  
Noah Burns

A concise and selective synthesis of the dichlorinated meroterpenoid azamerone is described. The paucity of tactics for the synthesis of chiral organochlorides motivated the development of unique strategies for accessing these motifs in enantioenriched forms. The route features a novel enantioselective chloroetherification reaction, a Pd-catalyzed cross-coupling between a quinone diazide and a boronic hemiester, and a late-stage tetrazine [4+2]-cycloaddition/oxidation cascade.


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