On Water: A practical and efficient synthesis of quinoxaline derivatives catalyzed by CuSO4· 5H2O

Montmorillonite K-10: An efficient and reusable catalyst for the synthesis of quinoxaline derivatives in water

“…The condensation reaction of 1,2-diamine with 1,2-dicarbonyl compounds follows the regular mechanism of acid-catalyzed condensation reactions [24], we assumed that the mechanism of the condensation reaction probably involve the complexation of Mont K-10 with the diketone by acting as an acid and also playing a complex role in promoting the dehydration to give a carbocationic intermediate as shown in Scheme 2: (i) coordination of a 1,2-dicarbonyl onto acid sites from Mont K-10, followed by (ii) the nucleophilic attack on the carbonly C providing I intermediate, (iii) dehydration to give a carbocation intermediate and (iv) elimination of a proton to give quinoxaline products. Yao et al [20] and Heravi et al [21] also reported that CAN and CuSO 4 AE 5H 2 O play a complex role in accelerating the dehydration steps, and thus promotes the formation of quinoxaline products. Using sulfamic acid as catalyst in an aqueous media, the reaction was slow with unsatisfactory yields.…”

“…The most common method is the condensation of an aryl-1,2-diamine with a 1,2-dicarbonyl compound in refluxing ethanol or acetic acid [11]. Improved methods have been reported for the synthesis of quinoxaline derivatives including the Bi-catalyzed oxidative coupling [12], a solid-phase synthesis [13], microwave [14], and the use of RuCl 2 -(PPh 3 ) 3 -TEMPO [15], MnO 2 [16], POCl 3 [17], zeolites [18], iodine [19], cerium ammonium nitrate [20], CuSO 4 AE 5H 2 O [21] and SA/MeOH [22] as catalyst or promoter. However, many of these processes suffer from one or other limitations such as drastic reaction conditions, low product yields, tedious work-up procedures, the use of toxic metal salts as catalysts, and relatively expensive reagents.…”

Synthesis of Thiophenyl Thiazole Based Novel Quinoxaline Derivatives

“…A variety of catalysts were tested in these reactions such as acetic acid [29], iodine [30], CuSO 4 .5H 2 O [31], nickel nanoparticles [32], gallium(III)triflate [33], montmorillonite K-10 [34], ionic liquids [35], Nano-TiO 2 [36], sulfated TiO 2 [37], Pd(OAc) 2 [38], RuCl 2 -(PPh 3 ) 3 -2,2,6,6-tetramethylpiperidine 1-oxyl(TEMPO) [38], MnO 2 [38], Al 2 O 3 [39], zirconium(IV)-modified silica gel [40], nanocrystalline CuO [41], cerium(IV) ammonium nitrate [42], iron exchanged molybdophosphoric acid [43], silica-bonded S-sulfonic acid [44], and sulfamic acid/MeOH [45]. Here we report synthesis of novel thiophene thiazole based quinoxaline derivatives by chloro-amine condensation.…”

Synthesis of some New Quinoxalines Bearing Pyridinyl Thiazole Moiety

“…In addition to common Lewis acids, many other catalysts including I 2 [20,21], SA [22], Montmorillonite K-10 [23], SSA [24] [26], MnCl 2 [27], CuSO 4 . 5H 2 0 [28], Zn/L-Proline [29] and CAN [30] have been explored. Oxidative couplings of epoxides and ene-1,2-diamines [31] catalyzed by Bi(0), Pd(OAc) 2 , RuCl 2 -(PPh 3 ) 3 -TEMPO, and MnO 2 have been reported [32][33][34].…”