Carbonyl–carbonyl (CO⋯CO) interactions are recently explored noncovalent interactions of significant interest owing to their role in the stability of biomacromolecules.

A series of isatin-3-ylidene (6a-i) and arylthiazolyl-1,3,4-oxadiazole-2-thione derivatives 7a-i derived from arylthiazolyl carbohydrazide analogs 4a-i were synthesized. Analogously, coupling of 4f with various amino acid methyl esters in the presence of HOBt/DCC reagents afforded the carboxamide derivatives 9a-d. The newly synthesized compounds were assayed against HIV-1 and HIV-2 in MT-4 cells. All compounds are inactive, except compounds 9b and 9c which showed inhibition of HIV-1 with EC 50 = 2.34 µg mL −1 , and 1.12 µg mL −1 with therapeutic indexes (SI) of 9 and <1, respectively.

To access the applications of a conformationally flexible molecule, thorough understanding of even the weak contributors to a particular conformation is necessary. We have synthesized and X-ray characterized a series...