Sabir H. Mashraqui

Catalytic oxidation of Hantzsch 1,4-dihydropyridines by RuCl3 under oxygen atmosphere

The first catalytic oxidation of Hantzsch 1,4-dihydropyridines is described using a catalytic amount (5 mol %) of RuCl3 in acetic acid under oxygen at room temperature. A tentative mechanism is proposed to account for the experimental observations.

An Expeditious and Convenient One Pot Synthesis of 2,5-Disubstituted-1,3,4-oxadiazoles

Abstract A convenient, one pot procedure is reported for the synthesis of a variety of 2,5-disubstituted-1,3,4-oxadiazoles by condensing mono-arylhydrazides with acid chlorides in HMPA solvent under the microwave heating. The yields are good to excellent, the process is rapid and does not need any added acid catalyst or dehydrating reagent.

Design of a dual sensing highly selective cyanide chemodosimeter based on pyridinium ring chemistry

A new chemodosimeter, Quino-P, recognizes the strongly nucleophilic cyanide by dual colorimetric and fluorescence ‘off–on’ signalling responses. Noteworthily, several other anions, even in significantly higher concentrations, induce no detectable photophysical perturbations. The chemodosimeter mechanism involves formation of a C4–cyano adduct, which exhibits an uncommon phenomenon of enhanced internal charge transfer interaction.

3-METHYL-2,3-DIHYDROBENZOTHIAZOLES AS REDUCING AGENTS - DYE ENHANCED PHOTOREACTIONS

Abstract Various types of electron deficient saturated carbon atoms are reduced in a visible light initiated process by N-alkyl-2,3-dihydrobenzothiazoles; these reactions are accelerated in the presence of Ru(bipy) 3 Cl 2 . The same ring system can act as an enolate carrier under electrophilic conditions.

Efficient Synthesis of 3‐Substituted Coumarins

Abstract The Mukaiyamas esterification protocol, using 2‐chloro‐1‐methylpyridinium iodide‐triethylamine reagent, has been successfully exploited to provide rapid access to a variety of 3‐substituted coumarins in satisfactory yields.

Bi(NO3)3.5H2O: A Convenient Reagent for Selective Oxidation of Sulfides to Sulfoxides

Abstract Bi(NO3)3.5H2O, a cheaply available, crystalline solid has been found to readily effect selective oxidation of a variety of sulfides to sulfoxides in acetic acid medium at room temperature in fair to good yields.

4,4-DIBROMO-3-METHYLPYRAZOL-5-ONE : NEW APPLICATIONS FOR SELECTIVE MONOBROMINATION OF PHENOLS AND OXIDATION OF SULFIDES TO SULFOXIDES

Abstract Dibromopyrazolone 1, a stable, crystalline solid effects para selective monobromination of phenols and aniline substrates under mild conditions. Selective oxidation of sulfides to sulfoxides can also be accomplished by using 1 in high yields.

A ring expansion method for the preparation of 2,3-dihydro-1,4-benzothiazines from 2-aryl-2,3-dihydrobenzothiazoles

Abstract In the presence of KF in dimethylformamide (DMF) 2-aryl-2,3-dihydrobenzothiazoles react with α-haloketones to provide in good yield 2,3-dihydro-2,3-disubstituted-1,4- benzothiazines.

Synthesis of 3,4-Bis (4′-Methylphenyl) Thieno [2,3-b]Thiophene: First Example of Peri-Diaryl Thienothiophene

Abstract 3,4-bis(4′-methylphenyl) thienothiophene, the first example of peri-(3,4) diaryl thienothiophene has been synthesized by a sequence involving preparation of ketene dithioacetal, Dieckmann type cyclization, ester hydrolysis and decarboxylation.

Condensation of Thioamides with 2-Aminothiophenols: A Versatile Synthesis of Benzothiazoles

Abstract Thioamides condense with 2-aminothiophenols under convenient and mild conditions to provide a variety of simple and functionalized benzothiazoles in fair to good yields.