Synthesis of 2‐substituted‐5‐rnethylthiazolo[ 3,2‐b ] ‐1,2,4‐lriazoles and acylatcd 3‐amino‐2‐imino‐4‐methyl‐2‐thiazolines

Abstract

3‐Amino‐2‐imino‐4‐mcthyl‐2‐thiazoline, 1, underwent ring closure with ethyl formate, cyanogen bromide and carbon disulfide, giving moderate yields of 2‐substituted‐5‐methylthiazolo[ 3,2‐b ]‐1,2,4‐triazoles, II. Reaction of I‐HCl with acid anhydrides (acetic, propionie, trifluoroacetic) resulted in the formation of the corresponding II compounds, whereas other anhydrides (benzoic, perfluoropropionic, perfluorobutyric) gave high yields of 3‐aeylamido‐2‐acylimido‐4‐melhyl‐2‐thiazolines. With acid chlorides and I‐HCl, in the presence of trielhylamine, mixtures of 2‐acyl‐irnino‐3‐aniino‐4‐methyl‐2‐thiazolines and 2‐aeylimino‐3‐(diacylamido)‐4‐methyl‐2‐thiazolines are formed. Spectral characteristics are reported.

Fused bicyclic 1,2,4‐triazoles with one extra sulfur atom: Synthesis, properties, and biological activity

“…During the next decade, researchers were actively involved in the investigation of new methods for obtaining thiazolotriazoles. [22][23][24][25] The condensation reactions of triazolethiones with α-halomethylcarbonyl compounds are the main methods for the synthesis of thiazolo [3,2-b] [1,2,4]triazoles 1. This reaction was carried out with acetone at room temperature in the presence of a base (NaOAc, Na 2 CO 3 ).…”

Heterocyclization of acylthiosemicarbazides

“…Thiazolyltriazole derivatives 143 were formed during the reaction of 141 with POCl 3 in xylene. The corresponding structural isomer 144 was obtained by reacting 142 with 26 in ethanol [178, 179].…”

Synthesis and chemistry of 3-tert-butyl-1,5-diaminopyrazoleCCDC reference number 211651. See http://www.rsc.org/suppdata/ob/b3/b306058f/ for crystallographic data in .cif or other electronic format.

“…in methanol (3 cm 3 ). The mixture was maintained at reflux temperature for 3 h. Removal of solvent gave a brown solid, 1-aza-1-( 5 (7), 210 (7), 138 (4) and 124 (9).…”

“…A solution of 1,5-diamino-3-tert-butylpyrazole 12 (0.171 g, 1.11 mmol) and ethyl 2-methylacetoacetate (0.160 g, 1.11 mmol) in acetic acid (3 cm 3 ) was heated under reflux for 1.5 h. The solvent was removed in vacuo to yield initially an oil. Trituration with ether gave a buff solid, 1H-8-tert-butyl-3,4-dimethylpyrazolo [1,5- (9) and 96 (11).…”

“…There is some precedent for this reaction, even in the 5-5 fused ring series. 9 On work-up of the thione 25 a semi-solid was obtained which showed many spots by TLC, but the mixture was directly alkylated (iodomethane, base) and the pyrazolo[1,5-b]1,2,4-triazole 26 was isolated as a yellow solid after column chromatography in 5.5% (unoptimised) yield. The product was characterised by mass spectrometry (m/z 210, M ϩ , 81%) and by 1 H NMR spectroscopy which showed a signal at δ H 5.61 due to the ring proton at the electron rich 7-position.…”