Ahmed H. Elghandour

Novel Cyanoketene N,S‐Acetals and Pyrazole Derivatives using Potassium 2‐Cyanoethylene‐1‐thiolates

Abstract Novel ketene N,S‐acetals 3 were readily prepared by the reaction of cyanoacetamide or cyanothioacetamide with phenylisothiocyanate in the presence of potassium hydroxide, followed by alkylation of the produced salts with methyl iodide. The reaction of compounds 3 with hydrazines afforded different substituted pyrazoles 6.

The structure of the products of coupling aryldiazonium salts with phenacylthiocyanates. Correction of literature reports

Abstract A variety of coupling products of phenacylthiocyanates 1a — d with aryldiazonium chlorides is reported. The i.r., u.v. 13 C NMR as well as the chemical behaviour of the coupling products clearly reveal that they are hydrazones ( 7 ) and not thiadiazol-2-imines ( 5 ) as previously reported.

Synthesis, 1H and 13C NMR Study of Pyrazoles Derived from Chiral Cyclohexanones (3-Methylcyclohexanone, Menthone, Pulegone, Dihydrocarvone and Carvone)

The 1 H and 1 3 C chemical shifts of four tetrahydroindazoles (two of them existing as diastereomeric mixtures) and one aldazine were measured and assigned. These compounds were obtained from monoterpenic ketones (R)-(+)-3-methylcyclohexanone, (2S,5R)-(-)-menthone, (R)-(+)-pulegone, (5R)-(+)-dihydrocarvone, and (R)-(-)-carvone in a two-step procedure. The annular tautomerism in CDCl 3 solution was calculated and compared with ab initio calculations (B3LYP/6-31G * ).

SYNTHESIS OF NOVEL DERIVATIVES OF 4-METHYLTHIO-N-ARYL-2-PYRIDONE AND DEAZAPURINE ANALOGUES: THE REACTION OF KETENE DITHIOACETALS WITH SUBSTITUTED ACETANILIDES

Abstract A new one-pot synthesis of 4-methylthio-N-aryl-2-pyridones and their deazapurine analogues by the reaction of ketene dithioacetals with substituted acetanilides have been reported.

Studies with polyfunctionally substituted heteroaromatics: synthesis of several new thiazoles, pyrazolo[5,1-c]triazines and of polyfunctionally substituted pyridines and pyrimidines.

Abstract Several thiazolin-4-one(3), 1,2,4-triazinethione (13), pyrazolo[1,5-c]-1,2,4-triazine (16) and pyridine (23) derivatives could be obtained via the reaction of iminoether (1) derivative with thioglycolic acid, aryldiazonium chloride, 3-arylpyrazol-5-yl diazonium chloride and alkylidenemalononitrile derivatives, respectively. The reaction mechanism for each one was discussed. All structure were suggested on the basis of elemental analyses and spectral data.

Potassium 2‐Cyanoethylene‐1‐thiolate Derivatives: A New Preparative Route to 2‐Cyanoketene S,N‐Acetals and Pyrazole Derivatives

Abstract The novel ketene S,N‐acetals 4a–e were readily prepared by the reaction of substituted cyanoacetanilides with phenylisothiocyanate in the presence of potassium hydroxide, followed by alkylation of the produced salts with methyl iodide. The reaction of compounds 4 with hydrazines afforded different substituted pyrazoles.

Cyanothioacetamide in heterocyclic chemistry: Synthesis of piperidine-3-carbonitrile, pyrazolopyridine, thiinopyridine-3-carbonitrile derivatives, and their theoretical calculations

Cyanothioacetamide ( 1 ) reacted with acrylonitrile ( 2 ) to afford the corresponding 6-oxo-2-sulfanylpiperidine-3-carbonitrile ( 6 ), which oxidized to give compounds 7 and 8 under different conditions. Moreover, compound 6 was used as a starting material to synthesize 12a-c , 16a-d , 26a-c , 27a-c , and 30a-c via reactions with aromatic aldehydes 9a-c , diazonium chlorides 13a-d , and 3-arylpropennitrile derivatives 18a-i respectively. Considering the data of IR, 1 H NMR, mass spectra, elemental analyses, and theoretical calculations, all the structures of the newly synthesized heterocyclic compounds were elucidated.

Reactions of hydrazonoyl halides 44 [1]: synthesis of some new 1,3,4-thiadiazolines, 1,3,4-selenadiazolines and triazolino[4,3- a ]pyrimidines

1,3,4-Thiadiazolines, 1,3,4-selenadiazolines and triazolino[4,3-a]pyrimidines have been synthesized from 3-aza-[2,4-dimethyl(1,3-thiazol-5-yl)-2-bromo-3-substituted-amino]prop-2-en-1-ones with potassium thiocyanate, potassium selenocyanate, alkyl carbodithioates and 6-methyl-2-methylthio-4-substituted 3,4-dihydropyrimidine-5-carboxylates. Structures of the newly synthesized compounds have been established by elemental analysis, spectral data and alternative synthesis whenever possible. Some of products have been tested towards bacteria.

Synthesis of Benzimidazole Ketene N , S -Acetals and Their Reactions with Nucleophiles

Abstract The novel ketene thioacetal 4 and ketene N,S-acetal 5 were readily prepared by the reaction of 2-cyanomethylbenzimidazole with either carbon disulfide or phenyl isothiocyanate in the presence of a base, followed by alkylation of the produced salts with methyl iodide. The reaction of compounds 4 and 5 with hydrazines afforded different benzimidazolyl substituted pyrazoles.

Novel Synthesis of Heterocyclic Ketene N,N-, N,O-, and N,S-Acetals Using Cyanoketene Dithioacetals

Abstract A novel synthesis of (2,3-dihydrobenzoimidazole-2-ylidenyl)cyano-acetanilide, (2,3-dihydrobenzoxazole-2-ylidenyl)cyanoacetanilide and (2,3-dihydro-benzothiazole-2-ylidenyl)cyanoacetanilide derivatives 5a–l via reaction of ketene dithioacetals 2a–d with o-phenylenediamine, o-aminophenol, and o-aminothiophenol 3a–c is reported and the synthetic potential of the method is demonstrated.