A recyclable and highly effective sulfamic acid/MeOH catalytic system for the synthesis of quinoxalines at room temperature

Fe3O4@SiO2/Schiff base complex of metal ions as an efficient and recyclable nanocatalyst for the green synthesis of quinoxaline derivatives

“…In contrast, electronwithdrawing groups such as nitro, benzoyl, and chloro gave slightly lower yields (Table 3, entries 12-18). Substrate bearing a strong electron-withdrawing NO 2 group gave lower yield even after longer reaction times (Table 3, entries [13][14][15]. On the other hand, electrondonating substituents associated with aromatic 1,2-diketone decreased the product yields and the effect is contrary with electron-withdrawing groups (Table 3, entries 2, 8, 15, and 17).…”

“…The condensation of 1,2-diamines with 1,2-diketones in refluxing ethanol or acetic acid has been used as a useful synthetic route toward quinoxalines (11). For this transformation, several catalysts and reagents have been reported, including a oxidative coupling method (12), ceric(IV) ammonium nitrate (13), sulfamic acid (14), a microwave procedure (15), zeolite (16) (36). However, these methods have many disadvantages, such as low yields, long reaction times, the use of toxic solvents, and harsh reaction conditions.…”

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

“…Initially, following the report by Darabi et al [22], we attempted the condensation of o-phenylenediamine and benzil (PhCOCOPh) using sulfamic acid (H 2 NSO 3 H, SA) in water, in place of MeOH, at room temperature for the synthesis of quinoxaline, resulting in the formation of a condensation product after 12 h (70%, Yield). Thus, 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.…”

Application of Sulfonic Acid Functionalized Nanoporous Silica (SBA-Pr-SO3H) for One-Pot Synthesis of Quinoxaline Derivatives

“…The yields of products were not good. Improved methods have been reported using the different catalysts including I 2 (Bhosale et al 2005, More et al 2005, SA (Darabi et al 2007), Montmorillonite K-10 (Huang et al 2008), polyaniline-sulfate salt (Srinivas et al 2007), H 6 P 2 W 18 O 62 . 24H 2 O , InCl 3 (Hazarika et al 2007), MnCl 2 (Heravi et al 2008), CuSO 4 .5H 2 O , Zn[(L)proline] , CAN (More et al 2006), Ga(OTf) 3 (Cai et al 2008), PEG-400 (Zhang et al 2010), Pd(OAc) 2 , MnO 2 (Raw et al 2003), keggin heteropoly acid (Huang et al 2009), and IBX (Heravi et al 2006) have been explored.…”