Saber M. Hassan

Heteroaromatization with Sulfonamido Phenyl Ethanone, Part I: Synthesis of Novel Pyrrolo[2,3-D]Pyrimidine and Pyrrolo[3,2-E][1,2,4]Triazolo[1,5-C]Pyrimidine Derivatives Containing Dimethylsulfonamide Moiety

4-(5-Amino-4-cyano-1-p-tolyl-1H-pyrrol-3-yl)-N,N-dimethyl-benzenesulfonamide (4) was prepared and converted to several pyrrolo[2,3-d]pyrimidin-5-yl)-N,N-dimethyl-benzenesulfonamide derivatives (5,7,9, and 13). Cyclocondensation of 13 with different electrophilic carbon reagents afforded several 4-(N,N-dimethylaminosulfonylphenyl)]pyrrolo[3,2-e][1,2,4]triazolo[1,5-c]-pyrimidine derivatives (14–17,19, and 20); IR, 1HNMR, and mass spectra of the newly synthesized compounds were recorded. Most of the obtained compounds were screened against Gram-positive and Gram-negative bacteria and fungi, for which some of these derivatives gave promising results.

Heteroaromatization with ketene dithioacetals: Part I. Synthesis of some novel 5-amino-1-(1,3,4-thiadiazol-2-yl) and 1-(1,3,4-thiadiazin-2-yl)pyrazole-4-carbonitriles

5-Amino-3-methylthio-1-(1,3,4-thiadiazol-2-yl) and 1-(1,3,4-thiadiazin-2-yl)pyrazole-4-carbonitriles have been prepared from 5-aminopyrazoles using ketene dithioacetals as starting materials.

Heteroaromatization with Sulfonamido Phenyl Ethanone, Part II: Synthesis of Novel Thiazolyl Acetonitriles and Thiazolyl Acrylonitriles and Their Derivatives Containing Dimethylsulfonamide Moiety

Thiazolyl acetonitrile (2) was prepared and converted to pyrazolo[5,1-c][1,2,4]triazine (5), thiazoline-4-one derivatives (10,12), thiazolo[3,2-a]pyridine (13), coumarin (14), and benzo[f]coumarin (16) derivatives through reactions with a variety of organic electrophiles and nucleophiles. Thiazolyl acrylonitrile derivatives (17, 18, 21, 26–28, 31–33) were also prepared, and their activity with a variety of reagents was investigated. The structure of these compounds was elucidated on the basis of elemental analysis, IR, 1H-NMR, and mass spectra. The antimicrobial and antifungal activities of the prepared compounds are also reported.

HETEROAROMATIZATION WITH KETENE DITHIOACETALS: PART II. SYNTHESIS OF SOME NOVEL 5-AMINOPYRAZOLE-3-CARBONITRILE, 3-CARBOXAMIDE AND PYRAZOLO[3,4-d]PYRIMIDIN-4-ONE DERIVATIVES AS ANTIMICROBIAL AGENTS

Abstract Ketene dithioacetals la-d are utilized for synthesis of pyrazoledithiocarboxylates 2a-d and arylaminopyrazoles 4a,b with two different substituents (o-ethoxy and p-diethylminosulfonyl) in aryl residue. Some transformation of the dithioesters 2 ate described. After that arylaminopyraroles 4a,b are converted to pyrazolopyrimidine derivatives 8–11.

Vibrational assignments, normal coordinate analysis, B3LYP calculations and conformational analysis of methyl-5-amino-4-cyano-3-(methylthio)-1H-pyrazole-1- carbodithioate

The Raman and infrared spectra of solid methyl-5-amino-4-cyano-3-(methylthio)-1H-pyrazole-1-carbodithioate (MAMPC, C7H8N4S3) were measured in the spectral range of 3700-100 cm(-1) and 4000-200 cm(-1) with a resolution of 4 and 0.5 cm(-1), respectively. Room temperature 13C NMR and (1)H NMR spectra from room temperature down to -60 °C were also recorded. As a result of internal rotation around C-N and/or C-S bonds, eighteen rotational isomers are suggested for the MAMPC molecule (Cs symmetry). DFT/B3LYP and MP2 calculations were carried out up to 6-311++G(d,p) basis sets to include polarization and diffusion functions. The results favor conformer 1 in the solid (experimentally) and gaseous (theoretically) phases. For conformer 1, the two -CH3 groups are directed towards the nitrogen atoms (pyrazole ring) and CS, while the -NH2 group retains sp2 hybridization and C-CN bond is quasi linear. To support NMR spectral assignments, chemical shifts (δ) were predicted at the B3LYP/6-311+G(2d,p) level using the method of Gauge-Invariant Atomic Orbital (GIAO) method. Moreover, the solvent effect was included via the Polarizable Continuum Model (PCM). Additionally, both infrared and Raman spectra were predicted using B3LYP/6-31G(d) calculations. The recorded vibrational, 1H and 13C NMR spectral data favors conformer 1 in both the solid phase and in solution. Aided by normal coordinate analysis and potential energy distributions, confident vibrational assignments for observed bands have been proposed. Moreover, the CH3 barriers to internal rotations were investigated. The results are discussed herein are compared with similar molecules whenever appropriate.

Preparation of new derivatives of thiazole, thiazolidine, and thiazol-2-ylpyrazolo[3,4-d]pyrimidine sulfonamido conjugates

Several new thiazoles ( 3–7 ), thiazolylpyrazole carbonitrile ( 10 , 11 ), and Thiazolidine sulfonamido conjugate derivatives ( 19–26 ) were prepared starting with p-Piperidinesulfonylacetophenones ( 1 , 2 ). The structure of these compounds was elucidated on the bases of elemental analysis, IR, PMR, and mass spectra. The antimicrobial activities of some selected compounds are also reported.

Chemistry and tautomerism of coupling products of diazotised sulfamethoxazole with some compounds containing an active methylene group

Azo compounds (2–5) bearing a sulfamethoxazole moiety were prepared. The action of hydrazinecarbodithioate derivatives on (2–4) afforded pyrazoledithiocarboxylates (8–10).

A Facile Synthesis of New Unsymmetrical Azines by Cyclodesulfurization Reactions of Dithioesters with Diamines

Abstract Dithioesters 2a, b were prepared and methylated to give dimethyl thioesters 3a, b. Azines 4a-d and 5a, b were obtained in one step from 2 with primary diamines or in two steps through 3. Dithioesters 2a, b reacted with amines in ethanol to produce thiosemicarbazones 6a, b and 8a–d, while in butanol reacted with morpholine to form 7a, b