2942-03-2Relevant articles and documents
In water organic synthesis: Introducing itaconic acid as a recyclable acidic promoter for efficient and scalable synthesis of quinoxaline derivatives at room temperature
Tamuli, Kashyap J.,Nath, Shyamalendu,Bordoloi, Manobjyoti
supporting information, p. 983 - 1002 (2021/02/27)
Substituted quinoxaline derivatives are traditionally synthesized by co-condensation of various starting materials. Herein, we describe a novel environmentally benign in water synthetic route for the synthesis of structurally and electronically diverse ninety quinoxalines with readily available substituted o-phenylenediamine and 1,2-diketones using cheap and biodegradable itaconic acid as a mild acid promotor in 1 hours. The reaction is performed at room temperature, which proceeds through cyclo-condensation reaction followed by obtaining the aforesaid nitrogen-containing heterocyclic adducts without performing the column chromatography up to 96% total yields. The simplicity, high efficiency, and reusable of the catalyst merits this reaction condition as “green synthesis” which enables it to be useful in synthetic transformations upto gram scale level.
Organocatalytic Green Approach Towards the Fabrication of Fused Benzo N,N-containing Heterocycles Facilitated by Ultrasonic Irradiation
Nongrum, Ridaphun,Kharmawlong, George Kupar,Rani, Jims World Star,Rahman, Noimur,Dutta, Arup,Nongkhlaw, Rishanlang
, p. 2873. (2019/08/26)
The development of a metal-free protocol for transformations in organic synthesis offers a significant potential environmental benefit. This article reports the exploration of meglumine, a nontoxic and biodegradable amino sugar, as an organocatalyst for the synthesis of biologically active 1H-dibenzo[b,e][1,4]diazepin-1-ones, highly regioselective benzimidazole derivatives and derivatives of quinoxalines. Operational simplicity, mild reaction conditions, shorter reaction times, and use of green solvents are the highlights of this protocol. The advantage of ultrasonic irradiation has been significantly explored for the synthesis of the aforesaid compounds. Furthermore, the multifaceted use of o-phenylenediamine has also been accentuated in the study.
An experimental and theoretical study of intramolecular regioselective oxidations of 6-substituted 2,3-dimethylquinoxaline derivatives
Peralta-Cruz, Javier,Díaz-Fernández, Mónica,ávila-Castro, Alberto,Ortegón-Reyna, David,Ariza-Castolo, Armando
, p. 5501 - 5515 (2016/07/06)
An experimental and theoretical study of the regioselective Riley oxidation was conducted on a series of 2,3-dimethyl-6-substituted-quinoxalines bearing EWG (NO2, CN, CF3, Cl, Br, F, COOH, COOMe, COPh) and EDG (2,3-dimethylquinoxaline, OMe, OH, NH2) substituents. The nitrogen lone pair of electrons of the symmetric benzopyrazine moiety initiates the oxidation and promotes nucleophilic competition between the two active sites to give carbaldehyde regioisomers a and b. The mesomeric effect provides the dominant contribution to the regioselectivity. The compounds were characterized by NMR, measuring the 1H, 13C, pfg-HSQC, pfg-HMBC, and 15N, 1H correlation signals established by pfg-HMQC. The nucleophilic reactivity of nitrogen was evaluated by 1H NMR titration and analyzed using Perrin linearization to determine the reactivity ratio, ΔK, of the N4 and N1 nitrogen atoms. The structures were optimized using density functional theory at the ωB97XD/6-311G++(d,p) level of theory. The highest occupied molecular orbitals modeled using the HF/6-311G++(d,p) functionals revealed an asymmetric electron density that confirmed the asymmetric nucleophilicity of the nitrogen centers. These values agreed with the experimentally measured ΔK ratios. The PM6 theoretical calculations of the heats of formation of the mesomeric forms and intermediates of (2,3-dimethyl-6-substituted-quinoxalines)-SeO2 allowed us to identify the reaction routes that minimized energy expenditures. The regioselectivities were explained in terms of the energetic diagrams of the regioisomers. All compounds evaluated indicated a preference toward forming regioisomer b, except for the derivative bearing the EDG substituent (2,3-dimethylquinoxaline) which displayed a preference for regioisomer a.
