scholarly journals Transition-metal-free C(sp3)–H/C(sp3)–H dehydrogenative coupling of saturated heterocycles with N-benzyl imines

2020 ◽  
Vol 11 (29) ◽  
pp. 7619-7625 ◽  
Author(s):  
Zhengfen Liu ◽  
Minyan Li ◽  
Guogang Deng ◽  
Wanshi Wei ◽  
Ping Feng ◽  
...  
Keyword(s):  
Hydrogen Atom ◽  
Transition Metal ◽  
Electron Donors ◽  
Metal Free ◽  
Aryl Radicals ◽  
Dehydrogenative Coupling ◽  
Saturated Heterocycles

A unique transition-metal-free C(sp3)–H/C(sp3)–H dehydrocoupling of N-benzylimines with saturated heterocycles is presented using 2-azaallyl anions as super electron donors to initiate the generation of hydrogen atom abstracting aryl radicals.

scholarly journals Diazaphosphinanes as hydride, hydrogen atom, proton or electron donors under transition-metal-free conditions: thermodynamics, kinetics, and synthetic applications

2020 ◽  
Vol 11 (14) ◽  
pp. 3672-3679 ◽  
Author(s):  
Jingjing Zhang ◽  
Jin-Dong Yang ◽  
Jin-Pei Cheng
Keyword(s):  
Hydrogen Atom ◽  
Transition Metal ◽  
Proton Donor ◽  
Electron Donors ◽  
Metal Free ◽  
Hydride Hydrogen

A new 1,3,2-diazaphosphinane, serving as a formal hydride, hydrogen-atom or proton donor without transition-metal mediation was exploited thermodynamically and kinetically. And, its promising potentials in versatile syntheses have been demonstrated.

scholarly journals SET activation of nitroarenes by 2-azaallyl anions as a straightforward access to 2,5-dihydro-1,2,4-oxadiazoles

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Dong Zou ◽  
Lishe Gan ◽  
Fan Yang ◽  
Huan Wang ◽  
Youge Pu ◽  
...  
Keyword(s):  
Transition Metal ◽  
Experimental Evidence ◽  
Radical Anion ◽  
Reaction Pathway ◽  
Cycloaddition Reaction ◽  
Electron Donors ◽  
Ring Closure ◽  
Computational Studies ◽  
Metal Free ◽  
Radical Coupling

AbstractThe use of nitroarenes as amino sources in synthesis is challenging. Herein is reported an unusual, straightforward, and transition metal-free method for the net [3 + 2]-cycloaddition reaction of 2-azaallyl anions with nitroarenes. The products of this reaction are diverse 2,5-dihydro-1,2,4-oxadiazoles (>40 examples, up to 95% yield). This method does not require an external reductant to reduce nitroarenes, nor does it employ nitrosoarenes, which are often used in N–O cycloadditions. Instead, it is proposed that the 2-azaallyl anions, which behave as super electron donors (SEDs), deliver an electron to the nitroarene to generate a nitroarene radical anion. A downstream 2-azaallyl radical coupling with a newly formed nitrosoarene is followed by ring closure to afford the observed products. This proposed reaction pathway is supported by computational studies and experimental evidence. Overall, this method uses readily available materials, is green, and exhibits a broad scope.

scholarly journals Transition-Metal-Free Radical C(sp3)–C(sp2) and C(sp3)–C(sp3) Coupling Enabled by 2-Azaallyls as Super-Electron-Donors and Coupling-Partners

2017 ◽  
Vol 139 (45) ◽  
pp. 16327-16333 ◽  
Author(s):  
Minyan Li ◽  
Simon Berritt ◽  
Lucas Matuszewski ◽  
Guogang Deng ◽  
Ana Pascual-Escudero ◽  
...  
Keyword(s):  
Free Radical ◽  
Transition Metal ◽  
Electron Donors ◽  
Metal Free

scholarly journals Synthesis of 2-oxindoles via 'transition-metal-free' intramolecular dehydrogenative coupling (IDC) of sp2 C–H and sp3 C–H bonds

2016 ◽  
Vol 12 ◽  
pp. 1153-1169 ◽  
Author(s):  
Nivesh Kumar ◽  
Santanu Ghosh ◽  
Subhajit Bhunia ◽  
Alakesh Bisai
Keyword(s):  
Transition Metal ◽  
Alkyl Halides ◽  
One Pot ◽  
Metal Free ◽  
Quaternary Center ◽  
Dehydrogenative Coupling ◽  
Carbon Carbon Bonds ◽  
Carbon Bonds

The synthesis of a variety of 2-oxindoles bearing an all-carbon quaternary center at the pseudo benzylic position has been achieved via a ‘transition-metal-free’ intramolecular dehydrogenative coupling (IDC). The construction of 2-oxindole moieties was carried out through formation of carbon–carbon bonds using KOt-Bu-catalyzed one pot C-alkylation of β-N-arylamido esters with alkyl halides followed by a dehydrogenative coupling. Experimental evidences indicated toward a radical-mediated path for this reaction.

scholarly journals Organic super-electron-donors: initiators in transition metal-free haloarene–arene coupling

2014 ◽  
Vol 5 (2) ◽  
pp. 476-482 ◽  
Author(s):  
Shengze Zhou ◽  
Greg M. Anderson ◽  
Bhaskar Mondal ◽  
Eswararao Doni ◽  
Vicki Ironmonger ◽  
...  
Keyword(s):  
Transition Metal ◽  
Electron Donors ◽  
Metal Free

Transition-metal-free radical relay cyclization of vinyl azides with 1,4-dihydropyridines involving a 1,5-hydrogen-atom transfer: access to α-tetralone scaffolds

2020 ◽  
Vol 7 (22) ◽  
pp. 3638-3647
Author(s):  
Yangzhen Liao ◽  
Yu Ran ◽  
Guijun Liu ◽  
Peijun Liu ◽  
Xiaozu Liu
Keyword(s):  
Free Radical ◽  
Hydrogen Atom ◽  
Transition Metal ◽  
Hydrogen Atom Transfer ◽  
Atom Transfer ◽  
Metal Free ◽  
Vinyl Azides

The remote C(sp3)–H functionalization enabled by a radical-mediated 1,5-hydrogen-atom transfer (HAT) process using vinyl azides and 1,4-dihydropyridines as precursors has been described.

(Diacetoxyiodo)benzene-Mediated Transition-Metal-Free Amination of C(sp3)–H Bonds Adjacent to Heteroatoms with Azoles: Synthesis of N-Alkylated Azoles

Synlett ◽  
2018 ◽  
Vol 29 (18) ◽  
pp. 2432-2436 ◽  
Author(s):  
Can Jin ◽  
Weike Su ◽  
Bin Sun ◽  
Zhiyang Yan
Keyword(s):  
Free Radical ◽  
Transition Metal ◽  
Coupling Reaction ◽  
Metal Catalyst ◽  
Metal Free ◽  
Alternative Method ◽  
Dehydrogenative Coupling ◽  
Wide Range ◽  
Ready Access

A novel PhI(OAc)2-mediated cross-dehydrogenative coupling reaction of α-C(sp3)–H bonds adjacent to a hetero atom with various azoles has been developed, which provides an alternative method for constructing C–N bonds with high atom efficiency. This new protocol requires no metal catalyst and it provides ready access to a wide range of N-alkylated azole derivatives in moderate to excellent yields by using commercially available PhI(OAc)2 as the sole oxidant. Furthermore, the method is effective on a gram scale, which highlights the practicality of this transformation. The result of radical-captured experiments indicated that the transformation might involve a free-radical pathway.

scholarly journals Oxidative cross-dehydrogenative coupling (CDC) via C(sp2)–H bond functionalization: tert-butyl peroxybenzoate (TBPB)-promoted regioselective direct C-3 acylation/benzoylation of 2H-indazoles with aldehydes/benzyl alcohols/styrenes

RSC Advances ◽  
2021 ◽  
Vol 11 (23) ◽  
pp. 14178-14192
Author(s):  
Richa Sharma ◽  
Lalit Yadav ◽  
Ravi Kant Yadav ◽  
Sandeep Chaudhary
Keyword(s):  
Transition Metal ◽  
Benzyl Alcohols ◽  
Bond Functionalization ◽  
Metal Free ◽  
Tert Butyl ◽  
Dehydrogenative Coupling

An efficient transition-metal-free oxidative C(sp2)–H/C(sp2)–H cross-dehydrogenative coupling via C(sp2)–H bond functionalization for regioselective C-3 acylation/benzoylation of 2H-indazoles with aldehydes/benzyl alcohols/styrenes is reported.

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