Halogenations of 3-aryl-1H-pyrazol-5-amines

Synthesis ◽  
2021 ◽  
Author(s):  
Jing He ◽  
Yueting Wei ◽  
Yijiao Feng ◽  
Chuntian Li ◽  
Bin Dai ◽  
...  
Keyword(s):  
Room Temperature ◽  
Dual Role ◽  
Pyrazole Derivatives ◽  
Reaction Conditions ◽  
Metal Free

A direct C-H halogenation of 3-aryl-1H-pyrazol-5-amines with NXS (X = Br, I, Cl) as cheap and safe halogenating reagents at room temperature has been developed. This transformation provides an effective metal-free protocol towards the synthesis of novel 4-halogenated pyrazole derivatives with moderate to excellent yields. The method represents simple and mild reaction conditions, broad substrate scope as well as gram-scale synthesis. The utility of this procedure is established by further transformations of the 4-halogenated products. Mechanism studies show that DMSO plays a dual role of catalyst and solvent.

scholarly journals Halogenations of 3-aryl-1H-pyrazol-5-amines

2021 ◽  
Author(s):  
Jing He ◽  
Yueting Wei ◽  
Yijiao Feng ◽  
Chuntian Li ◽  
Bin Dai ◽  
...  
Keyword(s):  
Room Temperature ◽  
Dual Role ◽  
Pyrazole Derivatives ◽  
Reaction Conditions ◽  
Metal Free

A direct C-H halogenation of 3-aryl-1H-pyrazol-5-amines with NXS (X = Br, I, Cl) as cheap and safe halogenating reagents at room temperature has been developed. This transformation provides an effective metal-free protocol towards the synthesis of novel 4-halogenated pyrazole derivatives with moderate to excellent yields. The method represents simple and mild reaction conditions, broad substrate scope as well as gram-scale synthesis. The utility of this procedure is established by further transformations of the 4-halogenated products. Mechanism studies show that DMSO plays a dual role of catalyst and solvent.

scholarly journals 1,3-Dioxolan-4-Ones as Promising Monomers for Aliphatic Polyesters: Metal-Free, in Bulk Preparation of PLA

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2396
Author(s):  
Stefano Gazzotti ◽  
Marco Aldo Ortenzi ◽  
Hermes Farina ◽  
Alessandra Silvani
Keyword(s):  
Molecular Weight ◽  
Thermal Properties ◽  
Acid Catalyst ◽  
Monomer Conversion ◽  
Reaction Conditions ◽  
Aliphatic Polyesters ◽  
Metal Free ◽  
Weight Growth ◽  
Double Activation

The first example of solvent-free, organocatalyzed, polymerization of 1,3-dioxolan-4-ones, used as easily accessible monomers for the synthesis of polylactic acid (PLA), is described here. An optimization of reaction conditions was carried out, with p-toluensulfonic acid emerging as the most efficient Brønsted acid catalyst. The reactivity of the monomers in the tested conditions was studied following the monomer conversion by 1H NMR and the molecular weight growth by SEC analysis. A double activation polymerization mechanism was proposed, pointing out the key role of the acid catalyst. The formation of acetal bridges was demonstrated, to different extents depending on the nature of the aldehyde or ketone employed for lactic acid protection. The polymer shows complete retention of stereochemistry, as well as good thermal properties and good polydispersity, albeit modest molecular weight.

scholarly journals One-Pot, Metal-Free Synthesis of Dimethyl Carbonate from CO2 at Room Temperature

2020 ◽  
Vol 1 (3) ◽  
pp. 298-314
Author(s):  
Santosh Govind Khokarale ◽  
Thai Q. Bui ◽  
Jyri-Pekka Mikkola
Keyword(s):  
Ionic Liquid ◽  
Room Temperature ◽  
Dimethyl Carbonate ◽  
High Selectivity ◽  
Chemical Species ◽  
Side Reactions ◽  
Ambient Conditions ◽  
Reaction Conditions ◽  
One Pot ◽  
Metal Free

Herein, we report on the metal-free, one-pot synthesis of industrially important dimethyl carbonate (DMC) from molecular CO2 under ambient conditions. In this process, initially the CO2 was chemisorbed through the formation of a switchable ionic liquid (SIL), [DBUH] [CH3CO3], by the interaction of CO2 with an equivalent mixture of organic superbase 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU) and methanol. The obtained SIL further reacted with methyl iodide (CH3I) to form DMC. The synthesis was carried out in both dimethyl sulfoxide (DMSO) and methanol. Methanol is preferred, as it not only served as a reagent and solvent in CO2 capture and DMC synthesis, but it also assisted in controlling the side reactions between chemical species such as CH3I and [DBUH]+ cation and increased the yield of DMC. Hence, the use of methanol avoided the loss of captured CO2 and favored the formation of DMC with high selectivity. Under the applied reaction conditions, 89% of the captured CO2 was converted to DMC. DBU was obtained, achieving 86% recovery of its salts formed during the synthesis. Most importantly, in this report we describe a simple and renewable solvent-based process for a metal-free approach to DMC synthesis under industrially feasible reaction conditions.

Metal-free synthesis of aminomethylated imidazoheterocycles: dual role of tert-butyl hydroperoxide as both an oxidant and a methylene source

2018 ◽  
Vol 16 (44) ◽  
pp. 8620-8628 ◽  
Author(s):  
Om P. S. Patel ◽  
Nitesh Kumar Nandwana ◽  
Ajay Kumar Sah ◽  
Anil Kumar
Keyword(s):  
Carbon Source ◽  
Dual Role ◽  
Butyl Hydroperoxide ◽  
Metal Free ◽  
Tert Butyl ◽  
Tert Butyl Hydroperoxide

A metal-free method is developed for the aminomethylation of imidazoheterocycles with 2/4-aminoheterocycles using TBHP as a carbon source as well as an oxidant.

scholarly journals Dual Role of Glyoxal in Metal-Free Dicarbonylation Reaction: Synthesis of Symmetrical and Unsymmetrical Dicarbonyl Imidazoheterocycles

ACS Omega ◽  
2019 ◽  
Vol 4 (6) ◽  
pp. 10140-10150 ◽  
Author(s):  
Nitesh Kumar Nandwana ◽  
Om P. S. Patel ◽  
Manu R. Srivathsa ◽  
Anil Kumar
Keyword(s):  
Dual Role ◽  
Reaction Synthesis ◽  
Metal Free

A General Method for the Synthesis of 11H-indeno[1,2-b]quinoxalin-11-ones and 6H-indeno[1,2-b]pyrido[3,2-e]pyrazin-6-one Derivatives using Mandelic Acid as an Efficient Organo-catalyst at Room Temperature

2021 ◽  
Vol 08 ◽  
Author(s):  
Aditi Sharma ◽  
Gurpreet Kaur ◽  
Diksha Singh ◽  
Vivek Kumar Gupta ◽  
Bubun Banerjee
Keyword(s):  
Mandelic Acid ◽  
Room Temperature ◽  
Aqueous Ethanol ◽  
Low Cost ◽  
Catalytic Amount ◽  
Reaction Conditions ◽  
Metal Free ◽  
Naturally Occurring ◽  
Column Chromatographic ◽  
General Method

Aims: Synthesis of 11H-indeno[1,2-b]quinoxalin-11-ones as well as 6H-indeno[1,2-b]pyrido[3,2-e]pyrazin-6-one derivatives under greener conditions. Background: Quinoxaline and related skeletons are very common in naturally occurring bioactive compounds. Objective: Design a facile, green and organo-catalyzed method for the synthesis of 11H-indeno[1,2-b]quinoxalin-11-ones as well as 6H-indeno[1,2-b]pyrido[3,2-e]pyrazin-6-one derivatives. Methods: Both the scaffolds were synthesized via the condensation of ninhydrin and o-phenylenediamines or pyridine-2,3-diamines respectively by using a catalytic amount of mandelic acid as an efficient, commercially available, low cost, organo-catalyst in aqueous ethanol at room temperature. Results: Mild reaction conditions, use of metal-free organocatalyst, non-toxic solvent, ambient temperature, and no column chromatographic separation are some of the notable advantages of our developed protocol. Conclusion: In conclusion, we have developed a simple, mild, facile and efficient method for the synthesis of structurally diverse 11H-indeno[1,2-b]quinoxalin-11-one derivatives via the condensation reactions of ninhydrin and various substituted benzene-1,2-diamines using a catalytic amount of mandelic acid as a commercially available metal-free organo-catalyst in aqueous ethanol at room temperature. Under the same optimized reaction conditions, synthesis of 6H-indeno[1,2-b]pyrido[3,2-e]pyrazin-6-one derivatives was also accomplished with excellent yields by using pyridine-2,3-diamines instead of o-phenylenediamine.

scholarly journals The dual role of thiourea in the thiotrifluoromethylation of alkenes

2017 ◽  
Vol 8 (2) ◽  
pp. 1195-1199 ◽  
Author(s):  
Paolo Ricci ◽  
Tanatorn Khotavivattana ◽  
Lukas Pfeifer ◽  
Maurice Médebielle ◽  
John Richard Morphy ◽  
...  
Keyword(s):  
Dual Role ◽  
Metal Free

We report the stereoselective and metal-free trifluoromethylation of alkenes followed by S-cyclization using thiourea as the S-source and SET initiator.

Dual role of p-tosylchloride: copper-catalyzed sulfenylation and metal free methylthiolation of imidazo[1,2-a]pyridines

2016 ◽  
Vol 14 (7) ◽  
pp. 2282-2290 ◽  
Author(s):  
Chitrakar Ravi ◽  
Darapaneni Chandra Mohan ◽  
Subbarayappa Adimurthy
Keyword(s):  
Dual Role ◽  
Metal Free

Copper-catalyzed regioselective C-3 sulfenylation and metal-free thiomethylation of imidazo[1,2-a]pyridines using p-tosylchloride and dimethylsulfoxide as sources for sulfenylation and thiomethylation respectively has been described.

Role of graphene oxide as a heterogeneous acid catalyst and benign oxidant for synthesis of benzimidazoles and benzothiazoles

RSC Advances ◽  
2016 ◽  
Vol 6 (10) ◽  
pp. 8164-8172 ◽  
Author(s):  
Kiran B. Dhopte ◽  
Rahul S. Zambare ◽  
Anand V. Patwardhan ◽  
Parag R. Nemade
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Free Acid ◽  
Acid Catalyst ◽  
Dual Role ◽  
Metal Free ◽  
Active Metal ◽  
Reduced Graphene ◽  
Heterogeneous Acid Catalyst

Graphene oxide plays a dual role as active metal-free acid catalyst and as non-toxic oxidant for benzothiazole and benzimidazole synthesis. Isolated partially reduced graphene oxide was re-oxidized to regenerate the catalyst and restore its activity.

Sign in / Sign up

Export Citation Format

Share Document