scholarly journals Direct alkylation of N,N-dialkyl benzamides with methyl sulfides under transition metal-free conditions

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Can-Can Bao ◽  
Hui-Zhen Du ◽  
Yan-Long Luo ◽  
Bing-Tao Guan
Keyword(s):  
Transition Metal ◽  
Functional Group ◽  
Metal Catalysts ◽  
Transition Metal Catalysts ◽  
Amide Bond ◽  
Selective Synthesis ◽  
Lithium Diisopropylamide ◽  
Organometallic Reagents ◽  
Metal Free ◽  
Resonance Stabilization

AbstractAmides are a fundamental and widespread functional group, and are usually considered as poor electrophiles owing to resonance stabilization of the amide bond. Various approaches have been developed to address challenges in amide transformations. Nonetheless, most methods use activated amides, organometallic reagents or transition metal catalysts. Here, we report the direct alkylation of N,N-dialkyl benzamides with methyl sulfides promoted by the readily available base LDA (lithium diisopropylamide). This approach successfully achieves an efficient and selective synthesis of α-sulfenylated ketones without using transition-metal catalysts or organometallic reagents. Preliminary mechanism studies reveal that the deprotonative aroylation of methyl sulfides is promoted by the directed ortho-lithiation of the tertiary benzamide with LDA.

scholarly journals One Pot and Metal-Free Approach to 3-(2-Hydroxybenzoyl)-1-aza-anthraquinones

Molecules ◽  
2019 ◽  
Vol 24 (16) ◽  
pp. 3017
Author(s):  
Jiaqi Yuan ◽  
Qian He ◽  
Shanshan Song ◽  
Xiaofei Zhang ◽  
Zehong Miao ◽  
...  
Keyword(s):  
Transition Metal ◽  
Functional Group ◽  
Metal Catalysts ◽  
Transition Metal Catalysts ◽  
Inert Gas ◽  
One Pot ◽  
Metal Free ◽  
Mild Conditions ◽  
Anthraquinone Derivatives

Herein, a direct strategy to synthesize 3-(2-hydroxybenzoyl)-1-aza-anthraquinones with excellent efficiency, mild conditions, and benign functional group compatibility was reported. A variety of 3-formylchromone compounds were employed as compatible substrates and this protocol gave the 3-(2-hydroxybenzoyl)-1-aza-anthraquinone derivatives in good to excellent yields without inert gas and expensive transition metal catalysts. Some compounds displayed good anti-proliferative activities.

scholarly journals Transition-Metal-Free [3+2] Dehydration Cycloaddition of Donor-Acceptor Cyclopropanes With 2-Naphthols

2021 ◽  
Vol 9 ◽  
Author(s):  
Hua Zhao ◽  
Peng Shen ◽  
Dongru Sun ◽  
Hongbin Zhai ◽  
Yufen Zhao
Keyword(s):  
Transition Metal ◽  
Ring Opening ◽  
Metal Catalysts ◽  
Transition Metal Catalysts ◽  
Cyclization Reaction ◽  
Metal Free ◽  
Efficient Access ◽  
Donor Acceptor ◽  
Acid Catalyzed ◽  
Synthetic Application

A Brønsted acid-catalyzed domino ring-opening cyclization transformation of donor-acceptor (D-A) cyclopropanes and 2-naphthols has been developed. This formal [3+2] cyclization reaction provided novel and efficient access to the naphthalene-fused cyclopentanes in the absence of any transition-metal catalysts or additives. This robust procedure was completed smoothly on a gram-scale to afford the corresponding product with comparable efficiency. Furthermore, the synthetic application of the prepared product has been demonstrated by its transformation into a variety of synthetically useful molecules.

Transition Metal-Free Strategies for the Synthesis of C-1 Aryl Substituted Tetrahydroisoquinolines

Synthesis ◽  
2021 ◽  
Author(s):  
Pushpinder Singh ◽  
Aanchal Batra ◽  
Kamal Nain Singh ◽  
Mritunjay Mritunjay
Keyword(s):  
Transition Metal ◽  
Oxidative Coupling ◽  
Metal Salt ◽  
Toxic Metal ◽  
Transition Metal Catalysts ◽  
Bioactive Molecules ◽  
Chemical Waste ◽  
Organometallic Reagents ◽  
Metal Free ◽  
Synthetic Drugs

1-Aryl-1,2,3,4-tetrahydroisoquinolines are important structural motifs and are widely found in bioactive molecules, pharmaceutical and synthetic drugs. In view of increasing environmental awareness, the development of transition metal-free strategies for the synthesis of these compounds is highly desirable. Metal-free oxidative coupling and lithiation methodologies have emerged as effective tools in this area as they exclude the use of transition metal catalysts and help in reducing unwanted and toxic metal based chemical waste in the environment. This review highlights the recent advances in direct arylation of tetrahydroisoquinolines for the synthesis of title compounds in the absence of metal salt. Also, the emphasis has been put on the mechanistic considerations of these reactions. 1 Introduction 2 Arylation of tetrahydroisoquinolines via oxidative coupling 2.1 Arylation using Grignard reagents 2.2 Arylation using other organometallic reagents 2.3 Arylation using aryl organoboranes or arenes 3 Arylation of tetrahydroisoquinolines via lithiation 3.1 Intermolecular arylation 3.2 Intramolecular arylation 4 Conclusions and Outlook

Transition metal-free aroylation of NH-sulfoximines with methyl arenes

2015 ◽  
Vol 51 (80) ◽  
pp. 14889-14892 ◽  
Author(s):  
Ya Zou ◽  
Jing Xiao ◽  
Zhihong Peng ◽  
Wanrong Dong ◽  
Delie An
Keyword(s):  
Transition Metal ◽  
Organic Solvents ◽  
Metal Catalysts ◽  
Transition Metal Catalysts ◽  
Metal Free

An iodine-catalyzed N-aroylation of NH-sulfoximines with methyl arenes was herein demonstrated without participation of external organic solvents, transition metal-catalysts or ligands.

Recent advances in metal free- and late transition metal-catalysed hydroamination of unactivated alkenes

2015 ◽  
Vol 5 (4) ◽  
pp. 2017-2037 ◽  
Author(s):  
Elise Bernoud ◽  
Clément Lepori ◽  
Mohamed Mellah ◽  
Emmanuelle Schulz ◽  
Jérôme Hannedouche
Keyword(s):  
Transition Metal ◽  
Metal Catalysts ◽  
Transition Metal Catalysts ◽  
Late Transition Metal ◽  
Metal Free ◽  
Recent Advances ◽  
Late Transition

This Perspective article outlines some of the recent advancements in the development of (chiral) metal-free and late transition metal catalysts for hydroamination of unactivated alkenes.

scholarly journals One-pot synthesis of propynoates and propynenitriles

2017 ◽  
Vol 95 (2) ◽  
pp. 144-148 ◽  
Author(s):  
Fan Shu ◽  
Qingjuan Zheng ◽  
Wanrong Dong ◽  
Zhihong Peng ◽  
Delie An
Keyword(s):  
Low Temperature ◽  
Transition Metal ◽  
Functional Group ◽  
High Efficiency ◽  
Metal Catalysts ◽  
Transition Metal Catalysts ◽  
One Pot ◽  
Efficient Transformation ◽  
One Pot Synthesis ◽  
Substituted Acetylenes

An efficient transformation towards propynoates and propynenitriles is herein described. The practical methodology was conducted at low temperature (–78 or –60 °C) in a one-pot manner with the assistance of base rather than any transition metal catalysts. The base-induced protocol exhibits good functional group tolerance (up to 28 examples) and high efficiency (up to 92% yields) towards substituted acetylenes of great synthetic significance, which was also well demonstrated by the gram-scale reactions.

Transition-Metal-Free Aerobic Oxidative Cross-Coupling of Indoles with Arylidenemalononitriles

Synlett ◽  
2019 ◽  
Vol 31 (02) ◽  
pp. 194-198
Author(s):  
Aizhen Yang ◽  
Zheng Li
Keyword(s):  
Transition Metal ◽  
Efficient Method ◽  
Cross Coupling ◽  
Transition Metal Catalysts ◽  
High Yield ◽  
Atom Economy ◽  
Direct Construction ◽  
Organometallic Reagents ◽  
Metal Free ◽  
Mild Conditions

An efficient method for the direct construction of C(sp2)–C(sp2) bonds by aerobic oxidative cross-coupling of indoles with arylidenemalononitriles is described. Various [aryl(1H-indol-3-yl)methylene]malononitriles were efficiently synthesized by using air as an oxidant under mild conditions. The salient features for this protocol are no transition-metal catalysts, no organometallic reagents, high atom economy, high yield, mild conditions, and simple workup procedures.

Environmentally friendly synthesis of secondary amines via one-pot reductive amination over a heterogeneous Co–Nx catalyst

2017 ◽  
Vol 41 (20) ◽  
pp. 11991-11997 ◽  
Author(s):  
Liang Jiang ◽  
Peng Zhou ◽  
Zehui Zhang ◽  
Quan Chi ◽  
Shiwei Jin
Keyword(s):  
Transition Metal ◽  
Reductive Amination ◽  
Environmentally Friendly ◽  
Metal Catalysts ◽  
Transition Metal Catalysts ◽  
Secondary Amines ◽  
Selective Synthesis ◽  
One Pot ◽  
Earth Abundant

The application of earth-abundant transition metal catalysts in the mild and selective synthesis of secondary amines via the reductive amination method is very challenging.

Transition-Metal-Free Functionalization of Saturated and Unsaturated Amines to Bioactive Alkaloids Mediated by Sodium Chlorite

Synlett ◽  
2020 ◽  
Author(s):  
Fernando Sartillo-Piscil ◽  
Julio Romero-Ibañez ◽  
Lilia Fuentes
Keyword(s):  
Transition Metal ◽  
Precious Metals ◽  
Extraction Process ◽  
Metal Catalysts ◽  
Transition Metal Catalysts ◽  
Sodium Chlorite ◽  
Chemical Transformations ◽  
Metal Free ◽  
Cyclic Amines ◽  
Metal Catalyzed

AbstractNew approaches to the synthesis of alkaloids through the straightforward functionalization of C(sp3)–H and C(sp2)=C(sp2) bonds of simple five- and six-membered-ring N-heterocycles are highlighted. The direct functionalization of pre-existing N-heterocycles to advanced alkaloids intermediates is a chemical operation that commonly requires the intervention of transition or precious metals. Regardless the inherent unwanted waste production, the high economical cost of many transition-metal catalysts limits their use globally. Here, we account our efforts directed toward the synthesis of bioactive alkaloids under an economic and ecological fashion by using NaClO2 as the key activating or oxidizing reagent that substitutes the use of transition-metal catalysts. While undesired metal wastes are collected during the extraction process of a transition-metal-catalyzed reaction, innocuous NaCl is the commonly product waste when NaClO2 is employed in our chemical transformations. Beginning with the synthesis of 2,3-epoxyamides from allyl amines, we concluded with the functionalization of multiple and remote C(sp3)–H and C(sp3)–C(sp3) bonds in piperidine rings that enabled the preparation of important bioactive alkaloids. For the latter functionalization, a precise amount of co-oxidant reagent (NaOCl) and radical 2,2,6,6-tetramethylpiperidinyloxy (TEMPO) were needed.1 Introduction2 Direct Chemical Method for Preparing 2,3-Epoxyamides3 Dual C(sp3)–H Oxidation of Cyclic Amines to 3‑Alkoxyamine Lac­tams4 Electrochemical Deamination of 3-Alkoxyamine Lactams5 Direct C–H Oxidation of Piperazines and Morpholines to 2,3-Diketopiperazines and 3-Morpholinones, Respectively6 Transition-Metal-Free Triple C–H Oxidation7 Deconstructive Lactamization of Piperidines8 Conclusion

Schiff-base molecules and COFs as metal-free catalysts or silver supports for carboxylation of alkynes with CO2

2021 ◽  
Author(s):  
Lin Zhang ◽  
Ran Bu ◽  
Xiao-yan Liu ◽  
Peng-fei Mu ◽  
En-Qing Gao
Keyword(s):  
Schiff Base ◽  
Transition Metal ◽  
Co2 Fixation ◽  
Metal Catalysts ◽  
Transition Metal Catalysts ◽  
Terminal Alkynes ◽  
Metal Free ◽  
Mild Conditions

Carboxylating terminal alkynes with CO2 to produce propiolic acids is an atom-economic and high-value route for CO2 fixation and utilization, but the conversion under mild conditions needs transition metal catalysts....

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