Synthesis of Pyrazolylthiazole and Pyrazolyl-1,2,4-Triazepine Derivatives

A convenient stereoselective access to novel 1,2,4-triazepan-3-ones/thiones via reduction or reductive alkylation of 7-membered cyclic semicarbazones and thiosemicarbazones

Stereoselective syntheses of 1-unsubstituted and 1-alkylsubstituted 1,2,4-triazepane-3-thiones/ones based on reduction or reductive alkylation of 2,4,5,6-tetrahydro-3H-1,2,4-triazepine-3-thiones/ones are reported.

Crystal structure of (E)-2-(5-(4-fluorophenyl)-3-(furan-2-yl)-4,5-dihydro-1H-pyrazol-1-yl)-5-((4-fluorophenyl)diazenyl)-4-methylthiazole, C23H17F2N5OS

C23H17F2N5OS, monoclinic, P21/c (no. 14), a = 5.2272(4) Å, b = 26.7398(15) Å, c = 15.2645(10) Å, β = 97.726(7)°, V = 2114.2(2) Å3, Z = 4, R gt(F) = 0.0547, wR ref(F 2) = 0.1371, T = 296(2) K.

Thiocarbamate-Based Synthesis of 2,4,5,6-Tetrahydro-3H-1,2,4-Triazepine-3-Thiones

A five-step synthesis of 5,7-diaryl-substituted 2,4,5,6-tetrahydro-3H-1,2,4-triazepine-3-thiones starting from ethyl thiocarbamate was developed. The synthesis included a three-component condensation of ethyl thiocarbamate with aromatic aldehydes and p-toluenesulfinic acid to give O-ethyl[(aryl)(tosyl)methyl]thiocarbamates which were transformed into the corresponding O-ethyl (3-phenyl-3-oxopropyl) thiocarbamates by treatment with the sodium enolate of dibenzoylmethane followed by base-promoted retro-Claisen condensation. Reaction of the prepared thiocarbamates with hydrazine and subsequent acid-catalysed cyclisation of the derived 4-[(3-hydrazono-3-phenyl)prop-1-yl]semicarbazides gave the target triazepines.

Advances in 1,2,4-triazepines chemistry

This review reports the chemistry of 1,2,4-triazepines. Heterocyclic 1,2,4-triazepines are mono and fused cycles.