Synthesis of aryl substituted 2,4,5,6-tetrahydro-3H-1,2,4-triazepine-3-thiones/ones starting from chalcone-derived β-isothiocyanato ketones

Different Modes of Acid-Promoted Cyclooligomerization of 4-(4-Thiosemicarbazido)butan-2-one Hydrazone: 14-Membered versus 28-Membered Polyazamacrocycle Formation

Unprecedented self-assembly of a novel 14-membered cyclic bis-thiosemicarbazone or/and a 28-membered cyclic tetrakis-thiosemicarbazone upon acid-promoted cyclooligomerization of 4-(4-thiosemicarbazido)butan-2-one hydrazone has been discovered. A thorough study of the influence of various factors on the direction of macrocyclization provided the optimal conditions for the highly selective formation of each of the macrocycles in excellent yields. Plausible pathways for macrocyclizations have been discussed. The macrocycle precursor was prepared by the reaction of readily available 4-isothiocyanatobutan-2-one with an excess of hydrazine.

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.