Straightforward Access to Pyrazines, Piperazinones, and Quinoxalines by Reactions of 1,2-Diaza-1,3-butadienes with 1,2-Diamines under Solution, Solvent-Free, or Solid-Phase Conditions

Abstract

The preparation of tetrahydropyrazines, dihydropyrazines, pyrazines, piperazinones, and quinoxalines by 1,4-addition of 1,2-diamines to 1,2-diaza-1,3-butadienes bearing carboxylate, carboxamide, or phosphorylated groups at the terminal carbon and subsequent internal heterocyclization is described. The solvent-free reaction of carboxylated 1,2-diaza-1,3-butadienes with the same reagents affords piperazinones, while phosphorylated 1,2-diaza-1,3-butadienes yield phosphorylated pyrazines. The solid-phase reaction of polymer-bound 1,2-diaza-1,3-butadienes with 1,2-diamines produces pyrazines.

Synthesis of Pyrazines from Rhodium-Catalyzed Reaction of 2H-Azirines with N-Sulfonyl 1,2,3-Triazoles

“…Ethyl acetate was the best solvent among several reaction media examined (dichloroethane, chloroform, toluene, chlorobenzene, n-hexane, cyclohexane, and ethyl acetate). A number of rhodium(II) catalysts were tested to reveal that Rh 2 (Oct) 4 (2.0 mol %) was the catalyst of choice. The best result was obtained from a reaction of 1a (1.0 equiv, 0.2 mmol) with 2a (1.5 equiv) using Rh 2 (Oct) 4 (2.0 mol %) in ethyl acetate at 120°C for 16 h, producing ethyl 3-(4-nitrophenyl)-5-phenylpyrazine-2-carboxylate (3aa) in 70% isolated yield (entry 10).…”

“…A number of rhodium(II) catalysts were tested to reveal that Rh 2 (Oct) 4 (2.0 mol %) was the catalyst of choice. The best result was obtained from a reaction of 1a (1.0 equiv, 0.2 mmol) with 2a (1.5 equiv) using Rh 2 (Oct) 4 (2.0 mol %) in ethyl acetate at 120°C for 16 h, producing ethyl 3-(4-nitrophenyl)-5-phenylpyrazine-2-carboxylate (3aa) in 70% isolated yield (entry 10). When the present reaction was conducted with Rh 2 (OAc) 4 (2.0 mol %) at or below 100°C, dihydropyrazines 4 and 5 were produced (entries 8 and 9).…”

An Efficient and Recyclable Nanoparticle-Supported Cobalt Catalyst for Quinoxaline Synthesis

“…Other protocols to synthesize quinoxalines mainly involve the oxidative trapping of vicinal diols or α-hydroxy ketones with 1,2-diamines [35][36][37][38][39][40][41][42], 1,4-addition of 1,2-diamines to diazenylbutenes [43], coupling of epoxides with ene-1,2-diamines [44,45], 2-nitroanilines with phenethylamines [46], alkynes or ketones with 1,2-diamines via a key oxidation process [47][48][49][50][51]. Therefore, the development of efficient methods for accessing quinoxalines derivatives continues to be an active area of research.…”

Synthesis of benzimidazole and quinoxaline derivatives using reusable sulfonated rice husk ash (RHA-SO3H) as a green and efficient solid acid catalyst

“…These compounds are widely distributed in nature and exhibit a broad spectrum of biological activity, including antibacterial [15], antitubercular, antimicrobial, antifungal, antimalarial, anti-inflammatory, antileishmanial, and antitumor activities, as well as functioning as herbicides and insecticides [16]. So, they have been synthesized by many research groups using numerous methods involving the condensation of 1,2-diamines with a-diketones [17], diazenylbutenes [18] and epoxides [19]. Recent research groups have presented reports concerning the synthesis of different quinoxaline derivatives involving several environmentally friendly (''green'') methodologies, including recyclable catalysts, microwave-assisted synthesis and reactions in aqueous media [20].…”