Mononuclear heterocyclic rearrangements. Part 16. Kinetic study of the rearrangement of some ortho-substituted Z-phenylhydrazones of 3-benzoyl-5-phenyl-1,2,4-oxadiazole into 2-aryl-4-benzoylamino-5-phenyl-1,2,3-triazoles in dioxane-water and in benzene

Recent Developments in the Synthesis, Chemistry and Applications of the Fully Unsaturated 1,2,4-Oxadiazoles

“…24c The conversion, by cyclic voltammetry, of a series of 3-substituted 5-(bromodifluoromethyl)-1,2,4-oxadiazoles into the corresponding difluoromethyl anion allows access to a range of difluoromethyl substituted 1,2,4-oxadiazoles. 52 A theoretical study concerning the Boulton-Katritzky rearrangement of 3-formylamino-1,2,4-oxadiazole has appeared. 22b Similarly, a 5-chloro group can be displaced with a variety of nucleophiles, 7 for example, a sulfur nucleophile.…”

Studies on Azole-to-Azole Interconversion − An Interesting Case of Absence of a “Primary Steric Effect” in the Ring-Degenerate Equilibration betweenortho-Substituted 3-Aroylamino-5-methyl-1,2,4-oxadiazoles and 3-Acetylamino-5-aryl-1,2,4-oxadiazoles in Methanol

“…At first sight, the absence of steric effects may appear surprising; as a matter of fact we have recently observed (Scheme 5) that the kinetics of the rearrangement of orthosubstituted (Z)-phenylhydrazones of 3-benzoyl-5-phenyl-1,2,4-oxadiazole (12) into 2-aryl-4-benzoylamino-5-phenyl-1,2,3-triazoles (13) (like the 10/11 equilibrium, an example of the general class of monocyclic rearrangement of heterocycles [1Ϫ3] ) show [14] a significant contribution of the ''primary steric effect'' to the overall reactivity observed [15] in dioxane/water (at pS ϩ ϭ 3.80: ρ o,m,p ϭ Ϫ1.30, f ϭ Ϫ0.90, and δ ϭ 0.50; at pS ϩ ϭ 11.50: ρ o,m,p ϭ 2.23, f ϭ 0.31, and δ ϭ 1.51 in the presence of electron-withdrawing substituents). Scheme 5 To understand why the reactivities of 12 and of the 10/ 11 couple should be so differently affected by the steric component of proximity effects, comparison between the side chains involved in the rearrangement in the two systems appears relevant.…”

Uses of ethyl benzoylacetate for the synthesis of thiophene, thiazole, pyridine, and pyran derivatives with antitumor activities

“…In the market, there are many drugs such as thiazole, thiophene, and pyridine derivatives. For such excessive benefits, these compounds were used in many efficient synthetic transformations and are used as intermediates in many chemical reactions . It has been reported that many thiazole, thiophene, and pyrazole derivatives showed potent analgesic, anticonvulsant, anti‐inflammatory and antibacterial, antipyretics, antitumor, antiparasitic, antimicrobial, antihistaminic, antianexiety test in mice, antiarrhythmic, and serotonin antagonist .…”

“…For such excessive benefits, these compounds were used in many efficient synthetic transformations and are used as intermediates in many chemical reactions. [1][2][3][4][5][6][7][8][9][10] It has been reported that many thiazole, thiophene, and pyrazole derivatives showed potent analgesic, [11,12] anticonvulsant, anti-inflammatory and antibacterial, [13,14] antipyretics, [15] antitumor, [16,17] antiparasitic, [18] antimicrobial, [19] antihistaminic, [20] antianexiety test in mice, [21] antiarrhythmic, [22] and serotonin antagonist. [23] In the present work, we studied the reaction of ethyl benzoylacetate with some cyanomethylene reagents followed by reaction with elemental sulfur.…”

“…Ethyl 5-amino-4-cyano-3-phenylthiophene-2-carboxylate(4) Elemental sulfur (0.32 g, 0.01 mol) was added to a solution of compound 3 (2.40 g, 0.01 mol) in 1,4-dioxane (30 mL) containing triethylamine (0.50 mL). The reaction mixture was heated under reflux for 1 hour and then poured onto ice/water containing few drops of hydrochloric acid, and the formed solid product was collected by filtration.Yellow crystals from acetic acid yield (1.57 g, 58%), mp 160-162 C, IR (KBr) νmax 3452, 3339 (NH 2 ), 2980 (CH 2 ), 2221 (CN), 1687 (C=O), 1623 (C=C);1 H NMR (DMSO-d 6 , 200 MHz): δ = 1.25 (t, 3H, J = 6.59 Hz, CH 3 ), 4.24 (q, 2H, J = 6.59 Hz, CH 2 ), 4.79 (s, 2H, D 2 O exchangeable, NH 2 ), 7.28-7.39 (m, 5H, C 6 H 5 ); 13 C NMR (DMSO-d 6 , 75 MHz): δ 16.3 (OCH 2 CH 3 ), 50.3 (OCH 2 CH 3 ), 116.8 (CN), 120.8, 123.2, 126.9, 129.0 (C 6 H 5 ), 164.5 (CO).…”