Recent progress of synthesis of new arylazoazoles based on bis(carbothioamides)

Angular Regioselective Synthesis of Varied Functionalized Hexahydro-1,2,4-triazolo[4,3-a]quinazolin-9-ones and Their Antiproliferative Action

New 2-thioxopyrimidin-4-ones capable of participating in regioselective reactions with functionally diverse hydrazonoyl chlorides towards angular regioisomers, rather than linear ones, were designed and synthesized to form stereoisomeric cis- and trans-hexahydro [1,2,4]triazolo[4,3-a]quinazolin-9-ones to be tested as antitumor candidates. The angular regiochemistry of the products was verified through crystallographic experiments and NMR studies. In addition, the regioselectivity of the reaction was found to be independent of the stereochemistry of the used 2-thioxopyrimidin-4-one. Only compound 4c demonstrated satisfactory growth inhibition against all the cancer cells used among all the produced drugs.

Efficient Methods for the Synthesis of Novel Arylazothiazoles Based on Acetylferrocene or Adamantane

BACKGROUND

Hydrazonoyl halides are convenient for the synthesis of arylazothiazoles.

MATERIALS AND METHODS

A series of novel arylazothiazoles were efficiently synthesized from the reaction of hydrazonoyl chlorides with 2-(adamantan-2-ylidene)hydrazinecarbothioamide or 2-(ferrocenyl-1-ylidene)hydrazinecarbo-- thioamide in dioxane used as an aprotic solvent because of its lower toxicity and higher boiling point (101 °C) and triethylamine at reflux. The reaction mechanistic pathway proceeded by the nucleophilic substitution reaction by the elimination of hydrogen chloride to give thiohydrazonates as intermediate, which in situ undergo intramolecular cyclization and loss of water molecule to afford the final product of novel arylazothiazoles. This method is simple with good yield and excellent purities.

RESULTS AND DISCUSSION

The synthetic schemes for the final products are proposed and discussed. The chemical structures of the final products were identified by different techniques, such as elemental analysis, Fourier-transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), and mass spectrometry (MS).

CONCLUSION

In this article, we prepared arylazothiazoles from the reaction of 2-(adamantan-2-ylidene)hydrazinecarbothioamide or 2-(ferrocenyl-1-ylidene)hydrazinecarbothioamide with hydrazonoyl halides.