quaternary carbon
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RSC Advances ◽  
2022 ◽  
Vol 12 (2) ◽  
pp. 785-789
Author(s):  
Seoung-Mi Choi ◽  
Kyeong Do Kim ◽  
Jong-Un Park ◽  
Zi Xuan ◽  
Ju Hyun Kim

A facile route to access N-fused pyrrolidines bearing a quaternary carbon from N-sulfonyl ketimines and commercially available trimethylenemethanes has been developed.


Author(s):  
Kaikai wang ◽  
Yanli Li ◽  
Yingchao Zhao ◽  
Aili sun ◽  
Rongxiang Chen ◽  
...  

A general approach to substituted pyrrolidines via [3 + 2] 1,3-dipolar cycloaddition between nonstabilized azomethine ylides and cyanosulfones was developed. The efficient method provides a series of substituted pyrrolidines bearing a quaternary carbon center in high yields (up to 98%) excellent diastereoselectivities (up to >25:1 dr) under ambient reaction conditions.


2021 ◽  
Author(s):  
Aaron Pan ◽  
Maja Chojnacka ◽  
Robert Crowley ◽  
Lucas Gottemann ◽  
Brandon Haines ◽  
...  

Dual Brønsted/Lewis acid catalysis involving environmentally benign, readily accessible protic acid and iron promotes site-selective tert-butylation of electron-rich arenes using di-tert-butylperoxide. This transformation inspired the development of a synergistic Brønsted/Lewis acid catalyzed aromatic alkylation that fills a gap in the Friedel–Crafts reaction literature by employing unactivated tertiary alcohols as alkylating agents, leading to new quaternary carbon centers. Corroborated by DFT calculations, the Lewis acid serves a role in enhancing the acidity of the Brønsted acid. The use of non-allylic, non-benzylic, and non-propargylic tertiary alcohols represents an underexplored area in Friedel–Crafts reactivity.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Dongquan Zhang ◽  
Miaomiao Li ◽  
Jiajia Li ◽  
Aijun Lin ◽  
Hequan Yao

AbstractThe Alder–ene type reaction between alkenes and alkynes provides an efficient and atom-economic method for the construction of C-C bond, which has been widely employed in the synthesis of natural products and other functional molecules. The intramolecular enantioselective Alder-ene cycloisomerization reactions of 1,n-enynes have been extensively investigated. However, the intermolecular asymmetric version has not been reported, and remains a challenging task. Herein, we describe a rhodium-catalyzed intermolecular enantioselective Alder-ene type reaction of cyclopentenes with silylacetylenes. A variety of chiral (E)-vinylsilane tethered cyclopentenes bearing one quaternary carbon and one tertiary carbon stereocenters are achieved in high yields and enantioselectivities. The reaction undergoes carbonyl-directed migratory insertion, β-H elimination and desymmetrization of prochiral cyclopentenes processes.


2021 ◽  
pp. 153495
Author(s):  
Yuichiro Kawamoto ◽  
Naoki Noguchi ◽  
Daiki Ozone ◽  
Toyoharu Kobayashi ◽  
Hisanaka Ito

2021 ◽  
Author(s):  
Smruti Ranjan Mohanty ◽  
Namrata Prusty ◽  
Shyam Kumar Banjare ◽  
Tanmayee Nanda ◽  
Ponneri C. Ravikumar

An earth-abundant and inexpensive Mn(I)-catalyzed alkylation of 2-pyridone with maleimide has been reported for the first time, in contrast to previously reported Diels-alder product. The directing group was easily removed after functionalization. Notably, unexpected migration of pyridine ring has been discovered in presence of acetic acid, which also provides unique class of compounds with three different N-heterocycles with an all-carbon quaternary carbon center. Furthermore, single crystal X-ray and HRMS revealed a five-membered manganacycle intermediate. This methodology tolerates a wide variety of functional groups delivering the alkylated products in moderate to excellent yields.


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