Synthesis of AZT analogues: 7-(3-azido-2-hydroxypropyl)-, 7-(3-amino-2-hydroxypropyl)-,7-(3-triazolyl-2-hydroxypropyl)theophylline

Synthesis and Antioxidant Activity of Novel 5-amino-2-alkyl/glycosylthio-1,3,4- thiadiazoles: Regioselective Alkylation and Glycosylation of the 5-amino-1,3,4- thiadiazole-2-thiol Scaffold

OBJECTIVE

5-Amino-2-alkyl/glycosylthio-1,3,4-thiadiazoles have been synthesized by the reaction of 5-amino-1,3,4-thiadiazole-2-thiol with a variety of alkylating agents or glycosyl halides in the presence of anhydrous potassium carbonate in dry acetone.

METHODS

The structures of the newly synthesized compounds have been established based on their spectral data (FT-IR, 1H- and 13C-NMR) and mass spectrometry. They were tested for their antioxidant behaviour by the use of 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging method. The in silico pharmacokinetics ADME properties of the potent antioxidant compounds were investigated by using Accelrys Discovery Studio (DS) 2.5 software.

RESULTS AND CONCLUSION

Regioselective alkylation and glycosylation of 5-amino-1,3,4-thiadiazole-2-thiol were noticed during its reaction with alkylating agents and glycosyl halides. Alkylating agents gave the Sfunctionalized derivatives, while the acetylated glycosyl halides afforded the S-glycosylated products together with their respective N-acetyl derivatives. The benzoylated glycosyl halide behaved in a different manner and gave N-glycoside analogue of 1,3,4-thiadiazole-2(3H)-thione, in addition to the expected sulfanyl S-glycoside. Most of the synthesized compounds showed noticeable antioxidant activity with respect to ceftriaxone as a standard drug. Some of the most active compounds showed acceptable predicted pharmacokinetics and druglikeness properties.

Synthesis of bis-acyclonucleoside analogues bearing benzothienyl-1,2,4-Triazol-3-Yl-disulfide under conventional and microwave methods

The oxidation of 5-(3-chlorobenzo[b]thien-2-yl)-4H-1,2,4-triazole-3-thiol (1) with a solution of iodine and potassium iodide at room temperature afforded [5-(3-chlorobenzo[b]thien-2-yl)-4H-1,2,4-triazole-3-yl]disulfide (2). In contrast, when the reaction mixture was heated or irradiated by MW, an unexpected additional product was obtained and identified as 3-(3-chlorobenzo[b]thien-2-yl)-4H-1,2,4-triazole (3); the ratio of products was 3:1. The preferred conformer of 2 was deduced from the theoretical calculation. The alkylation of compounds 2 and 3 with epichlorohydrin and hydroxyalkylating agents gave the corresponding N,N-bis- and N-acyclonucleosides analogues 8-15.

Synthesis and antiviral evaluation of novel 2,3-dihydroxypropyl nucleosides from 2- and 4-thiouracils

Regioselective alkylation of 2-thiouracils 1a-c and 4-thiouracils 7a,b with 2,3-O-isopropylidene-2,3-dihydroxypropyl chloride (2) afforded 2-[[(2,2-Dimethyl-1,3-dioxolan-4-yl) methyl]thio]pyrimidin-4(1H)-ones 3a-c and 4-[[(2,2-Dimethyl-1,3-dioxolan-4-yl)methyl]thio] pyrimidin-2(1H)-ones 8a,b, respectively. Further alkylation with 2 and/or 2,3-O-isopropylidine-1-O-(4-toluenesulfonyl)-glycerol (4) gave the acyclo N-nucleosides 5a-c and 9a,b whose deprotection afforded 6a-c and 10a,b. 2-(Methylthio)pyrimidin-4(1H)-ones 11a-c and 4-(methylthio)pyrimidin-2(1H)-ones 14a,b were treated with 2 and/or 4 to give 12a-c and 15a,b which were deprotected to give 13a-c and 16a,b. Pyrimidine-2,4(1H,3H)-dithiones 17a-c were treated with two equivalents of 2 to give 2,4-bis[[(2,2-dimethyl-1,3-dioxolan-4-yl)methyl]thio] pyrimidines 18a-c. Deprotection of compounds 18a-c gave 2,4-bis[(2,3-dihydroxypropyl)thio]pyrimidines 19a-c. The activity of the deprotected nucleosides against Hepatitis B virus was evaluated and showed moderate inhibition activity against HBV with mild cytotoxicity.

Novel regioselective hydroxyl-alkylation of 4,5-diphenylimidazole-2-thione and a competitive intramolecular ring closure of the S-hydroxyalkyl-imidazoles to imidazo[2,1-b]thiazines and thiazoles. Role of catalyst, microwave irradiation, and solid support

Under both conventional method (CM) and microwave (MW) irradiation (MWI) conditions, alkylation of 4,5-diphenylimidazole-2-thione (1) with halogeno-alkanols 2 or 5, chloroglycerol 11 and 2,3-O-isopropylidene-1-O-(p-tolylsulfonyl)-glycerol (8) in presence of sodium ethoxide or sodium acetate in alcohol afforded regioselectively the corresponding S-alkylated analogues 3, 6, 9, and 12; they also were obtained using MW in absence and presence of bentonite as solid support with no change in regioselectivity. In the presence of potassium carbonate in DMF, the bisalkylated analogues 4, 7, 10, and 13 were obtained except in case of compound 13 where it was accompanied with the imidazothiazine 14. A convenient approach for imidazo-[2,1-b]thiazines and thiazoles 14-16 could be achieved by intramolecular dehydrative ring closure of the S-hydroxyalkylated imidazoles 3, 6, and 12 using potassium carbonate in DMF under both conventional and microwave methods. Isopropylidenation of 12 and 13 and deprotection of 9 and 10 also were investigated.