Maya P. Singh

Facile conversion of azides to amines

Les azides sont reduits en amines primaires par reaction avec le chlorure stanneux dans le methanol

Reductive Cleavage of Symmetrical Disulfides with Hydrazines

Abstract An efficient method for the reductive cleavage of symmetrical disulfides with hydrazines is described.

Synthesis and antibacterial activity of 7-hydrazinoquinolones

A series of new C-7 substituted hydrazino quinolones and naphthyridines were prepared and tested for antibacterial activity. The hydrazine bridge at the C-7 position did not favor the antibacterial activity, whereas the nature of other substituents at N-1, C-5 and C-8 did noticeably influence the antibacterial activity. The 7-(1-aminomorpholino) derivatives exhibited superior antibacterial activity against Gram-positive and inferior activity against Gram-negative bacteria than the 7-(1-aminopiperazinyl) derivatives. Substitution of the quinolone at position-1 with cyclopropyl was the most beneficial for antibacterial activity among the series of compounds prepared.

A Convenient Synthesis of Cephem-1R-sulfoxides

Abstract 7-Amidocephalosporins are converted to the 7-diacylaminocephalosporins, which are oxidised exclusively to the 7-diacylamino-1α-sulfoxides. These compounds with benzylamine produce the 7-amidocephem-1α-sulfoxides.

The trapping of sulfenic acids from penicillin sulfoxides - use of 2,5-dimercapto-1,3,4-thiadiazole and 2,4-dimercaptopyrimidine as trapping agents.

Abstract 2,5-Dimercapto-1,3,4-thiadiazole and 2,4-dimercaptopyrimidine were used to trap sulfenic acids from penicillin sulfoxides.

Synthesis and in vitro antimicrobial activity of 3-heteroarylsulphonylmethyl cephems: a new class of cephalosporins

Summary A series of 3-heteroarylsulphonylmethyl and 3-heteroarylsulphenylmethyl cephems were prepared and tested for antimicrobial activities. In contrast to the adverse effect of oxidized ring sulphur of penams and cephems on antimicrobial activities, the oxidized side-chain sulphur of 3-mercaptoheteroaryl cephems retained Gram-negative and slightly decreased Gram-positive activity. The chemical nature of the moieties substituted at C-7 and C-3 positions also influenced the antibacterial activity and spectrum. Compounds with thienyl substitution at C-7 and sulphonylmethylthiazoles or sulphonylmethylthiadiazoles at C-3 exhibited good differentials in antibacterial activity versus their unoxidized counterparts.

Synthesis and in vitro antibacterial activity of 2β and 2α-(substituted methyl) phenoxymethylpenicillins and an oxidation product

Abstract The effect of stereochemical changes on the antibacterial activity of a series of 2-substituted methyl-6β-phenoxyacetamido penams synthesized in our laboratory was studied. The 2α-heteroarylthiomethyl penams were found to be more active than the 2β-substituted derivatives against a range of Gram-positive and Gram-negative microorganisms. Both the isomers of 2-substituted methyl derivatives were found to be less active than the unsubstituted compound, the phenoxymethyl penicillin. The oxidized product of the 2α-isomer was less active than the unoxidized compound.