Raafat M. Shaker

Recent Trends in the Chemistry of 4-Amino-1,2,4-triazole-3-thiones

The synthesis and reactions of substituted 4-amino-1,2,4-triazole-5-thione derivatives as well as their biological activity are reviewed.

Ultrasound mediated green synthesis of rhodanine derivatives: Synthesis, chemical behavior, and antibacterial activity

GRAPHICAL ABSTRACT ABSTRACT A variety of rhodanine derivatives were synthesized via a three-component reaction of carbon disulfide, amines, and dialkyl acetylenedicarboxylate in polyethylene glycol under conventional stirring or ultrasound irradiation. The sonochemical-assisted procedure provides an improved and accelerated conversion when compared to the conventional reaction, with increased rate of reaction and quality of product obtained. The product formed, 2a, could be readily converted to bis-rhodanine under microwave conditions. Moreover, the pyranothiazoles 9a,b were prepared from the corresponding rhodanines 2a,b and malononitrile. Fifteen compounds were screened for their antibacterial activities against nine human, animal and plant pathogenic Gram-positive and Gram-negative bacteria using the agar well diffusion method. Out of these derivatives, compounds 2g and 2h were the most effective against all tested bacteria.

Synthesis, reactivity, and biological activity of 5-aminouracil and its derivatives

The synthesis and reactions of 5-aminouracil and its derivatives are comprehensively reviewed. A brief survey of biological activities, especially chemotherapeutic and pharmacological properties, is also reported.Graphical Abstract

5-Aminouracil as a Building Block in Heterocyclic Synthesis: Part I. One-pot Synthesis of Pyrimido(5,4-b)quinolin-2,4,9-triones under Microwave Irradiation without Catalyst

A series of 6,7,8,10-tetrahydropyrimido[5,4-b]quinolin-2,4,9-(1H,3H,5H)-triones 6 were synthesized through one-pot condensation of 5-aminouracil, aldehydes and dimedone in DMF under microwave irradiation without catalyst. The products 6a, d were oxidized to the 7,8-dihydro-pyrimido- [5,4-b]quinolin-2,4,9-(1H,3H,6H)-triones 11a, b. Treatment of 6a, d and/or 11a, b with ethyl iodide in the presence of anhydrous potassium carbonate gave the ethylated derivatives 12a, b and 13a, b, respectively. The structures of the products were confirmed by elemental analyses, IR, MS, 1H, and 13C NMR spectra.

A Facile Route to the Synthesis of New 2,3-Disubstituted Benzocoumarins

Abstract Triphenylphosphine catalyzes the reaction between 2-hydroxy-1-naphthaldehyde and π-deficient acetylenes to give the newly prepared benzo[f]chromenes. The mechanism for the formation of products is discussed.

5-Aminouracil as a Building Block in Heterocyclic Synthesis: Part III. One-pot Synthesis of Novel Pyrimido[5,4-b]quinoline-2,4,9-triones and Pyrimido[5,4-c]isoquinolines

An efficient and direct procedure for the synthesis of pyrimido[5,4-b]quinoline-2,4,9-trione and pyrimido[5,4-c]isoquinoline derivatives has been described. The products were characterized by elemental analyses, IR, 1H NMR, 13C NMR and MS spectra. Graphical Abstract 5-Aminouracil as a Building Block in Heterocyclic Synthesis: Part III. One-pot Synthesis of Novel Pyrimido[5,4-b]quinoline-2,4,9-triones and Pyrimido[5,4-c]isoquinolines

5-Aminouracil as a Building Block in Heterocyclic Synthesis, Part II. One-pot Synthesis of Pyrido[3,2-d:6,5-dʹ]dipyrimidines under Microwave Irradiation without Catalyst

An efficient and direct procedure for the synthesis of pyrido[3,2-d:6,5-dʹ]dipyrimidine derivatives under microwave-assisted conditions is been described. The structures of the products were characterized by elemental analyses, and their IR, 1H NMR, 13C NMR, and MS spectra. Graphical Abstract 5-Aminouracil as a Building Block in Heterocyclic Synthesis, Part II. One-pot Synthesis of Pyrido[3,2-d:6,5-dʹ]dipyrimidines under Microwave Irradiation without Catalyst