Synthesis of pyrazine‐2,3‐dicarbonitriles via the one‐pot three‐component reaction of 4‐benzoyl‐5‐phenylamino‐2,3‐dihydrothiophene‐2,3‐dione, diaminomaleonitrile, and functionalized alcohols in acetonitrile

Abstract

An efficient one-pot three-component reaction of 4-benzoyl-5-phenylamino-2,-3-dihydrothiophene-2,3-dione, diaminomaleonitrile, and alcohols with heteroatom substituents or several hydroxyl groups in acetonitrile solvent under reflux led to the formation of 5-(2-substituted ethoxy or propoxy-2-phenyl-1-Nphenylthiocarbamoylethenyl)-6-oxo-1,6-dihydropyrazine-2,3-dicarbonitrile derivatives in good yields.

Synthesis of Organic Ligands via Reactions of 4-Benzoyl-5-phenylamino-2,3-dihydrothiophene-2,3-dione with N-Nucleophiles

“…Orange powder (crystallized from 2-propanol); yield 0.31 g (71%); mp 98 °C-100 °C; IR (KBr): v 3397 (NH), 1700 (C�O, amide), 1638 (C�O, ketone), 1596 (C�C), 1579 (NH), 1542, 1387, 1138 (C-N, NH, C�S, thioamide) cm −1 ; 1 H NMR (DMSO-d 6 ): δ 3.00 (6H, s, 2CH 3 ), 5.19 (3H, br s, 3NH), 7.25 (7), 594 (2), 522 (5), 450 (5), 408 (5), 227 (7), 165 (10), 123 (11), 105 (22), 91 (26)…”

“…In addition, 4-acylated-5substituted thiophene-2,3-diones are feasible and beneficial intermediates for the synthesis of a vast variety of substituted heterocyclic compounds [17][18][19]. In addition, 4-benzoyl-5-phenylamino-2,3-dihydrothiophene-2,3dione (1) has been recognized as a particularly significant starting material or intermediate for the synthesis of diverse sulfur-and nitrogen-containing heterocyclic compounds [16,[20][21][22][23]. In the previous study, we found that the reactions of 4-benzoyl-5-phenylamino-2,3-dihydrothiophene-2,3-dione (1) with N-nucleophiles such as primary and secondary aliphatic amines and tertiary aromatic and aliphatic amines in THF/H 2 O (1 : 1) at room temperature gave amide derivatives that have N-phenylthiocarbamoyl group [20] while those with primary aromatic amines in ethanol at high temperature provided substituted thiophenes [16] (Scheme 1).…”