Green synthesis of 2-pyrazinones in deep eutectic solvents: From α-chloro oximes to peptidomimetic scaffolds

1,3‐Dipolar Cycloaddition of Alkanone Enolates with Azides in Deep Eutectic Solvents for the Metal‐Free Regioselective Synthesis of Densely Functionalized 1,2,3‐Triazoles

“…[9] More eco-friendly CuAAC procedures rely on either the use of water as the reaction medium under heterogeneous conditions [10] or the employment of biodegradable, environmentally responsible, nature-inspired Deep Eutectic Solvents (DESs) [11] under homogeneous [12] or heterogeneous [13] conditions. Building upon our recent findings on the preparation of enolates [14] and variously functionalized nitrogen heterocycles (e. g., pyrazines, imidazoles, pyrimidines, 2-aminoimidazoles, 2pyrazinones, benzoxazines) [15][16][17][18][19] directly in DESs, in this work we Notable features of our report include i) reactions run under mild conditions (room temperature), ii) broad substrate scope (26 examples) and high regioselectivity, with the desired educts prepared in good to excellent yields (up to 98 %), iii) ability to telescope enolate formation/click cycloaddition/reduction or etherification reactions in a one-pot process to synthesize valuable pharmacologically active triazole derivatives.…”

Green synthesis, cytotoxicity and antimicrobial activities of some new pyrazolines, pyrimidines and naphthyridines based on 1,3-di(thien-2-yl)prop-2-en-1-one using choline chloride-urea mixture as a deep eutectic solvent

“…In recent years, deep eutectic solvents (DESs) have attracted great attention as green solvents in many organic reactions and transformations [1][2][3][4][5][6][7][8]. DESs can be easily formulated via hydrogen bonding between two components, the first is hydrogen bond donor which can be acid [9], alcohol [10,11] carbohydrate [12] or amide [13,14] and the second is hydrogen bond acceptor as quaternary ammonium salt [14,15].…”

Regiodivergent synthesis of functionalized pyrimidines and imidazoles through phenacyl azides in deep eutectic solvents

“…As part of our ongoing research in DES chemistry, we reported recently on the preparation of valuable heterocycles by (a) nucleophilic substitution (tetrahydrofuran derivatives) [4], (b) heterocyclodehydration reactions (2-aminoimidazoles, 2-pyrazinones, benzoxazines, thiophenes) [5][6][7][8], (c) carbon-sulfur bond-forming reactions [9], (d) directed ortho-metalation and nucleophilic acyl substitution strategies [10], (e) Pd-catalyzed aminocarbonylation of aryl iodides, Suzuki-Miyaura and Sonogashira cross-coupling reactions [11][12][13], (f) Cu-catalyzed C-N coupling reactions [14], and (g) heterogeneous "click" cycloaddition reactions [15] using DESs as environmentally responsible and non-innocent reaction media. Telescoped, one-pot transformations of phenacyl halides to symmetrical 2,5-disubstituted pyrazines (A), through phenacyl azides as intermediates, were also found to take place smoothly using such neoteric solvents (Scheme 1, path a) [16].…”