scholarly journals Metal-free formal synthesis of phenoxazine

2018 ◽  
Vol 14 ◽  
pp. 1491-1497 ◽  
Author(s):  
Gabriella Kervefors ◽  
Antonia Becker ◽  
Chandan Dey ◽  
Berit Olofsson
Keyword(s):  
Reaction Time ◽  
Transition Metal ◽  
Formal Synthesis ◽  
Metal Free ◽  
Diaryl Ether ◽  
Diaryliodonium Salt ◽  
Moderate Yield ◽  
Stable Iodine

A transition metal-free formal synthesis of phenoxazine is presented. The key step of the sequence is a high-yielding O-arylation of a phenol with an unsymmetrical diaryliodonium salt to provide an ortho-disubstituted diaryl ether. This species was cyclized to acetylphenoxazine in moderate yield. The overall yield in the three-step sequence is 72% based on recovered diaryl ether. An interesting, unusually stable iodine(III) intermediate in the O-arylation was observed by NMR and could be converted to the product upon longer reaction time.

scholarly journals Base-Catalyzed Synthesis of Flavones via Thiol-Assisted Sequential Demethylation/Cyclization of 1-(2-methoxyphenyl)prop-2-yn-1-ones

2021 ◽  
Author(s):  
Ritiele Heck ◽  
Thiago Anjos ◽  
Maira R Giehl ◽  
Ricardo F Schumacher ◽  
Benhur Godoi
Keyword(s):  
Reaction Time ◽  
Secondary Metabolites ◽  
Transition Metal ◽  
Intramolecular Cyclization ◽  
Important Class ◽  
Short Reaction Time ◽  
Metal Free ◽  
Synthetic Strategy ◽  
Pharmacologically Active ◽  
Active Substances

Flavone and analogues represent an important class of biologically and pharmacologically active substances commonly found in the composition of diverse plants as part of the class of secondary metabolites. Herein, we have demonstrated an efficient and regioselective synthetic strategy for the preparation of functionalized flavones through sequential demethylation/6-endo-dig intramolecular cyclization of propyn-1-ones, using catalytic amounts of base in the presence of a thiol, by employing NMP as the solvent. The reactions proceeded smoothly under transition-metal-free and open to air conditions, furnishing the desired six-membered heterocycles in moderate to excellent yields, in short reaction time.

scholarly journals Transition-Metal-Free Synthesis of a Known Intermediate in the Formal Synthesis of (-)-Steganacin

2016 ◽  
Vol 2017 (3) ◽  
pp. 497-503 ◽  
Author(s):  
David Augros ◽  
Boubacar Yalcouye ◽  
Sabine Choppin ◽  
Matthieu Chessé ◽  
Armen Panossian ◽  
...  
Keyword(s):  
Transition Metal ◽  
Formal Synthesis ◽  
Metal Free

Transition-metal-free catalytic hydroboration reduction of amides to amines

2020 ◽  
Vol 7 (21) ◽  
pp. 3515-3520
Author(s):  
Wubing Yao ◽  
Jiali Wang ◽  
Aiguo Zhong ◽  
Shiliang Wang ◽  
Yinlin Shao
Keyword(s):  
Transition Metal ◽  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Value Added ◽  
Metal Free

The selective catalytic reduction of amides to value-added amine products is a desirable but challenging transformation.

Deaminative carbonylative thioesterification of activated alkylamines with thiophenols under transition-metal-free conditions

2021 ◽  
Author(s):  
Fengqian Zhao ◽  
Xiao-Feng Wu
Keyword(s):  
Free Radical ◽  
Transition Metal ◽  
Metal Free

A transition-metal-free radical carbonylation of activated alkylamines with thiophenols has been successfully developed. Various thioesters were selectively produced with moderate to good yields.

Regioselective C3-H Trifluoromethylation of 2H-Indazole Under Transition-Metal-Free Photoredox Catalysis

2019 ◽  
Author(s):  
Arumugavel Murugan ◽  
Venkata Nagarjuna Babu ◽  
Nagaraj Sabarinathan ◽  
Sharada Duddu. S
Keyword(s):  
Transition Metal ◽  
Visible Light ◽  
Practical Approach ◽  
Hypervalent Iodine ◽  
Radical Mechanism ◽  
Photoredox Catalysis ◽  
Metal Free

Here we report a visible-light-promoted metal-free regioselective C3-H trifluoromehtylation reaction that proceeds via radical mechanism and which supported by control experiments. The combination of photoredox catalysis and hypervalent iodine reagent provides a practical approach for the present trifluoromethylation reaction and synthesis of a library of trifluoromethylated indazoles.

Selective Oxidation of Alcohols Catalyzed by a Transition Metal-Free System of NHPI/DDQ/NaNO2

2011 ◽  
Vol 32 (1) ◽  
pp. 118-122 ◽  
Author(s):  
Lipeng ZHOU ◽  
Chaofeng ZHANG ◽  
Tao FANG ◽  
Bingbing ZHANG ◽  
Ying WANG ◽  
...  
Keyword(s):  
Transition Metal ◽  
Selective Oxidation ◽  
Free System ◽  
Metal Free ◽  
Oxidation Of Alcohols

Defect engineering and characterization of active sites for efficient electrocatalysis

Nanoscale ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 3327-3345
Author(s):  
Xuecheng Yan ◽  
Linzhou Zhuang ◽  
Zhonghua Zhu ◽  
Xiangdong Yao
Keyword(s):  
Transition Metal ◽  
Active Sites ◽  
Defect Engineering ◽  
Metal Free

This review highlights recent advancements in defect engineering and characterization of both metal-free carbons and transition metal-based electrocatalysts.

Transition metal free, green and facile halogenation of ketene dithioacetals using a KX–oxidant system

2021 ◽  
Author(s):  
Vishakha Rai ◽  
Ganesh Shivayogappa Sorabad ◽  
Mahagundappa Rachappa Maddani
Keyword(s):  
Transition Metal ◽  
Ambient Temperature ◽  
Metal Free ◽  
Ketene Dithioacetals ◽  
System P ◽  
Oxidative Halogenation ◽  
Potassium Halide

A facile oxidative halogenation of α-oxo ketene dithioacetals is achieved by using a potassium halide and an oxidant combination under transition metal free conditions at ambient temperature.

Highly chemoselective deoxygenation of N-heterocyclic N-oxides under transition metal-free conditions

2021 ◽  
Vol 19 (16) ◽  
pp. 3735-3742
Author(s):  
Se Hyun Kim ◽  
Ju Hyeon An ◽  
Jun Hee Lee
Keyword(s):  
Transition Metal ◽  
Visible Light ◽  
Eosin Y ◽  
Metal Free ◽  
Simple Protocol

Here, we provide an operationally simple protocol for the highly chemoselective deoxygenation of various functionalized N-heterocyclic N-oxides under visible light-mediated photoredox conditions with Na2-eosin Y as an organophotocatalyst.

scholarly journals Transition-Metal-Free Cross-Coupling of Aryl Halides with Arylstannanes

2021 ◽  
Author(s):  
Qing He ◽  
Wenli Wang ◽  
Yong Liang ◽  
Zunting Zhang ◽  
Stanislaw F. Wnuk
Keyword(s):  
Transition Metal ◽  
Cross Coupling ◽  
Aryl Halides ◽  
Metal Free
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