Thiohydantoin Nucleosides. Synthesis Approaches

Summary. Several thiohydantoin N-nucleosides and their S-glycosides were prepared via different approaches which involved the direct glycosylation of the free thiohydantoin bases or their silylated derivatives with the corresponding sugar moieties in the presence of base or Lewis acid. Deprotection was carried out in acidic or basic medium. The site of N- and/or S-glycosylation was determined by NMR and UV measurements. In similar manner, hydantoin nucleosides were prepared.Present address: Riaydh Teachers College, P.O. Box 4341, Riaydh 11491, Saudi ArabiaPresent address: EuroMed-Konstanz, P.O. Box 100552, D-78405 Konstanz, Germany     

Efficient diverse approach for quinoxaline‐derived glycosylated and morphinylated analogs

Sulfanyl‐glycosides have been synthesized by reaction of 2,3‐dimercaptoquinoxaline ( 1 ) with acetohalo sugars in presence of base to give the thioglycosides‐derived quinoxalines 5 , 6 , 7 and 9 . Similarly, the acyclic analogs 23 , 24 , 25 , 26 were prepared by coupling of 1 with different acyclo‐alkylating agents. The preparation of 3‐morpholinyl‐quinoxalines 10 and 11 allowed the synthesis of 3‐glycosylsulfanyl‐2‐morpholinyl‐quinoxalines 12 , 13 , 14 and 17 as well as the acyclic analogs 27 , 28 , 29 . Microwave irradiation of the reactants turned out to be preferred over the conventional method for achieving the synthetic goals. This study made an available venue to the synthesis of diverse quinoxaline derivatives. J. Heterocyclic Chem., 2011.     

Effect of solvent on the regioselective synthesis of spiropyrazoles

1,3-Dipolarcycloaddition reactions of 6-arylmethylene-6,7,8,9-tetrahydro-5H-benzocyclohepten-5-ones (1) with nitrilimines 3 were investigated in benzene and chloroform. The reaction products were 2′,4′,6,7,8,9-hexahydro-2′,4′,5′-triaryl spiro[benzocycloheptene-6(5H),3′(3H-pyrazol)-5-ones (4) or 2′,3′,6,7,8,9-hexahydro-2′,3′,5′-triaryl spiro[benzocycloheptene-6(5H),4′(4H-pyrazol)-5-ones (5). X-ray crystallographic analysis was carried out for compound 5b. It was found that the regioselectivity of the produced compounds was altered based on changing solvent type.     

Synthesis and antiviral activity of new substituted pyrimidine glycosides

A number of N‐substituted pyrimidine glycosides were synthesized by coupling reaction of the pyrimidine base with acetobromosugars followed by deprotection. The synthesized compounds were tested for their antiviral activity against Hepatitis B Virus (HBV). Plaque reduction infectivity assay was used to determine virus count reduction as a result of treatment with tested compounds which showed moderate to high anti viral activities. J. Heterocyclic Chem., (2011).