Synthesis of new chiral 1,3,4-thiadiazole-based di- and tri-arylsulfonamide residues and evaluation of in vitro anti-HIV activity and cytotoxicity.

A series of new chiral 1,3,4-thiadiazole-based bis-sulfonamides 4a-4w and tri-sulfonamide analogue 5 was synthesized and evaluated as anti-HIV agents. The reaction of chiral amino acids 1 with sulfonyl chlorides 2, followed by subsequent reaction of resultant N-protected amino acids 2a-2f with thiosemicarbazide in the presence of excess phosphorous oxychloride afforded N-(1-(5-amino-1,3,4-thiadiazol-2-yl)alkyl)-4-arylsulfonamides 3a-3f. Treatment of 2a-2f with substituted sulfonyl chlorides in portions furnished the target bis-sulfonamide analogues 4a-4w in good yields, together with the unexpected 5. The new compounds were assayed against HIV-1 and HIV-2 in MT-4 cells. Compounds 4s were the most active in inhibiting HIV-1 with IC50 = 9.5 µM (SI = 6.6), suggesting to be a new lead in the development of an antiviral agent. Interestingly, compound 5 exhibited significant cytotoxicity of > 4.09 µM and could be a promising antiproliferative agent.