Transition metal-free generation of the acceptor/acceptor-carbene via α-elimination: synthesis of fluoroacetyl cyclopropanes

2016 ◽  
Vol 52 (41) ◽  
pp. 6817-6820 ◽  
Author(s):  
Yongdong Wang ◽  
Jing Han ◽  
Jie Chen ◽  
Weiguo Cao
Keyword(s):  
Transition Metal ◽  
Ring Expansion ◽  
Metal Free ◽  
Free Generation

An efficient transition metal-free approach for the generation of acceptor/acceptor-carbene followed by trapping with alkenes to provide fluoroacetyl cyclopropanes has been described. The resulting cyclopropanes could be further converted into the fluoromethyl dihydrofurans or fluorodihydropyrroles through ring-expansion processes.

scholarly journals Synthesis of Trifluoromethylated Cycloheptatrienes from N-Tosylhydrazones: Transition-Metal-Free Büchner Ring Expansion

Synlett ◽  
2014 ◽  
Vol 26 (01) ◽  
pp. 59-62 ◽  
Author(s):  
Xi Wang ◽  
Jianbo Wang ◽  
Zhikun Zhang ◽  
Jiajie Feng ◽  
Yan Xu ◽  
...  
Keyword(s):  
Transition Metal ◽  
Ring Expansion ◽  
Metal Free

Sonication and Microwave-Assisted Primary Amination of Potassium­ Aryltrifluoroborates and Phenylboronic Acids under Metal-Free Conditions

Synthesis ◽  
2017 ◽  
Vol 49 (11) ◽  
pp. 2555-2561 ◽  
Author(s):  
Dale Kuik ◽  
J. McCubbin ◽  
Geoffrey Tranmer
Keyword(s):  
Transition Metal ◽  
Reaction Times ◽  
Aqueous Sodium Hydroxide ◽  
Metal Free ◽  
Microwave Assisted ◽  
Free Generation ◽  
Phenylboronic Acids ◽  
Microwave Assisted Method ◽  
General Method ◽  
Electron Withdrawing Substituents

The transition-metal-free generation of a series of primary arylamines from potassium aryltrifluoroborates and phenylboronic acids­ is reported. The method uses a mild, inexpensive source of nitrogen (hydroxylamine-O-sulfonic acid) in cooperation with aqueous sodium hydroxide in acetonitrile. Both a sonication and a microwave-assisted method were developed, which are capable of converting ArBF3K functionalities into primary arylamines (ArNH2) in isolated yields of up to 78% (10 examples for each method). This report represents the first general method for the conversion of aryltrifluoroborates into primary arylamines under mild, transition-metal-free conditions in moderate to very good yields. The method is applicable to a wide array of substrates containing electron-donating, electron-neutral, or electron-withdrawing substituents. Both the sonication and microwave methods were also applied to the generation of anilines from phenylboronic acids in isolated yields of up to 96% (12 examples for each method) that were superior to existing room temperature methods in terms of yield, while also offering much shorter reaction times (15 min vs 16 h). In particular, the microwave method is the first to allow for the conversion of arylboronic acids containing strongly electron-withdrawing substituents into the corresponding anilines in good yields, along with electron-donating­ substituents in very good to excellent yields.

Transition-Metal-Free Synthesis of Substituted Pyridines via Ring Expansion of 2-Allyl-2H-azirines

2014 ◽  
Vol 16 (13) ◽  
pp. 3432-3435 ◽  
Author(s):  
Yaojia Jiang ◽  
Cheol-Min Park ◽  
Teck-Peng Loh
Keyword(s):  
Transition Metal ◽  
Ring Expansion ◽  
Metal Free ◽  
Substituted Pyridines

Transition-Metal-Free Access to Heteroaromatic-Fused 4-Tetralones by the Oxidative Ring Expansion of the Cyclobutanol Moiety

2019 ◽  
Vol 84 (15) ◽  
pp. 9611-9626 ◽  
Author(s):  
Philipp Natho ◽  
Lewis A. T. Allen ◽  
Andrew J. P. White ◽  
Philip J. Parsons
Keyword(s):  
Transition Metal ◽  
Ring Expansion ◽  
Free Access ◽  
Metal Free ◽  
Oxidative Ring Expansion

Regioselective Transition-Metal-Free Oxidative Cyclobutanol Ring Expansion to 4-Tetralones

2018 ◽  
Vol 20 (24) ◽  
pp. 8030-8034 ◽  
Author(s):  
Philipp Natho ◽  
Mia Kapun ◽  
Lewis A. T. Allen ◽  
Philip J. Parsons
Keyword(s):  
Transition Metal ◽  
Ring Expansion ◽  
Metal Free
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