Nora M. Rateb

Atom-Efficient, Solvent-Free, Green Synthesis of Chalcones by Grinding

Abstract An improved Claisen–Schmidt condensation reaction of methyl ketones and aromatic aldehydes can be achieved by grinding at room temperature in the absence of solvents. This process is simple, efficient, economical, and environmentally benign compared to classical reactions.

Reactions with Hydrazonoyl Halides XXX: Synthesis of Some 2,3-Dihydro-1,3,4-Thiadiazoles and Unsymmetrical Azines Containing Benzothiazole Moiety

Abstract C-Benzothiazoloyl-N-arylhydrazonoyl bromides 1a,b have been caused to react with each of methyl 2-thiazolylcyanomethinecarbodithioate (2), alkyl carbodithioates 8–10, and methyl thiocarbamates 14a-c in the presence of triethylamine to give 2,3-dihydro-1,3,4-thiadiazoles in good yields. In contrast, hydrazonoyl bromides react with each of phenylthiourea (19a), phenylthiosemicarbazide (19b), and benzoylthiosemicarbazide (19c) afforded 5-arylazothiazole 22–24(a-c) derivatives, respectively. Structures of the new compounds were elucidated on the basis of elemental analyses, spectral data, and alternative methods of synthesis whenever possible.

Green synthesis and antimicrobial evaluation of some new trifluoromethyl-substituted hexahydropyrimidines by grinding

A series of trifluoromethyl-substituted hexahydropyrimidine derivatives were efficiently synthesized in excellent yields via one-pot three-component reaction of aromatic aldehydes, ethyl trifluoroacetoacetate and thiourea(urea) in presence of p-toluenesulfonic acid under solvent-free conditions at room temperature by grinding. The present method does not involve any hazardous organic solvent and has proven to be simple, efficient, environmentally benign and cost-effective compared with the classical synthetic methods. These compounds were screened for their antibacterial activities against Escherichia coli and Bacillus thuringiensis and found to exhibit remarkably better antibacterial activities than the control drug.

A simple and green procedure for the synthesis of 5-arylidene-4-thiazolidinones by grinding

Abstract An improved green Knoevenagel condensation of various aromatic aldehydes with 4-thiazolidinones in the presence of anhydrous ammonium acetate can be achieved by grinding at room temperature in the absence of solvents. This process is simple, efficient, economical, and environmentally benign compared to classical reactions.

Reactions of Hydrazonoyl Halides 35 1 : Synthesis of Some New 1,2,4-Triazolino[4,3-a]pyrimidines, 2,3-Dihydro-1,3,4-thiadiazoles and 2,3-Dihydro-1,3,4-selenadiazoles

Hydrazonoyl halides have been caused to react with each of ethyl 4-(2 H -benzo[3,4- d ]1,3-dioxolen-5-yl)-6-methyl-2-methylthio-3,4-dihydropyrimidin-5-carboxylate, potassium thiocyanate (or thiourea), potassium selenocyanate, and alkyl carbodithioate in the presence of triethylamine to give 4,3-dihydro-1,2,4-triazolino[4,3- a ]pyrimidine, 1,3,4-thiadiazoline, 1,2,4-selenadiazoline, and unsymmetrical azine derivatives in good yields. Structures of the new compounds were elucidated on the basis of elemental analyses, spectral data, and alternative methods of synthesis whenever possible.

Convenient Synthesis and Antimicrobial Evaluation of Multicyclic Thienopyridines

Thieno[2,3-b]pyridines 7, 8, and 10 could be obtained via the S-alkylation of 3-cyano-4,6-di-2-furyl-2(1H)pyridinethione (3) with a variety of alkylating agents. These compounds were conveniently converted into novel pyrido[3′,2′:4,5]thieno[3,2-d]pyrimidines 12–15 and 17–20 and thieno[2,3-b;4,5-b′]dipyridine 11 derivatives. Structures of the products have been determined by elemental analyses and spectral data studies. All the tested compounds were found to exhibit moderate antimicrobial activity.

Synthesis and antimicrobial evaluation of some new thienopyridine, pyrazolopyridine and pyridothienopyrimidine derivatives

Thieno[2,3-b]pyridines 7, 8, 9 were obtained via the S-alkylation of 3 with a variety of alkylating agents followed by cyclization in a basic medium. On the other hand, compound 3 reacted with methyl iodide to give compound 10 which was converted to pyrazolo[3,4-b]pyridine derivative 13 by reaction with hydrazine hydrate. Pyrido[3′, 2′:4,5]thieno[3,2-d]pyrimidines derivatives 14, 16 were obtained by reaction of 7 with each of formic acid and formic/formamide, respectively. Furthermore, compound 14 was obtained by the reaction of 8 with formamide. Structures of the newly synthesized products were determined by elemental analysis and spectral data.

REACTIONS WITH HYDRAZONOYL HALIDES XIX1: SYNTHESIS OF SOME PYRAZOLE AND 5-ARYLAZOTHIAZOLE DERIVATIVES

Abstract Hydrazonoyl chlorides 1 reacted with 2-aryl-1-cyano-1-thiazol-2-ylethenes 2 in presence of triethyl-amine to give the cycloadducts 4. which were converted to the corresponding pyrazoles 5 by the action of sodium methoxide. The reaction of hydrazonoyl halides 1 and 6 with each of 2-aryli-dene-2-cyanoethanethioamides 7 and 2-arylhydrazono-2-cyanoethanethioamides 14 in ethanolic tri-ethylamine or ethanolic sodium hydroxide solutions, has been investigated. Structures of all the products were established on the basis of their spectral data and alternative synthesis.

A Facile and Convenient Method for the Synthesis of Bis-Hydrazonoyl Halides and Bis-(1,3,4-Thiadiazol-3-ylphenoxy)Ethers

Abstract New bis(thiadiazole) derivatives 7a–m were prepared in good yields by the reaction of the appropriate hydrazonoyl halides 4a–e with the bis-Schiff bases 9a–c. Similarly, the bis(thiadiazole) derivatives 17a–g were prepared by the reaction of the novel bis-hydrazonoyl halides 13a–d with schiff bases 3a–d.

Synthesis and reactions of 4-trifluoromethyl-3-cyano pyridine-2(1H)-thione/one derivatives

4,4,4-Trifluoro-1-(thiophen-2-yl)butane-1,3-dione was reacted by grinding with cyanothioacetamide and cyanoacetamide under solvent-free conditions at 25 °C to give pyridine-2(1H)thione/one derivatives in excellent yields. These compounds were further reacted by grinding with different halogenated reagents to give 2-S/O-alkyl pyridine derivatives. The latter compounds were utilized for the synthesis of thieno[2,3-b]pyridine, pyrazolopyridine, pyridothienopyrimidine and pyridothienooxazinone derivatives.