Yehia A. Ibrahim

Efficient synthesis of 3-aroylcinnolines from aryl methyl ketones

Abstract An efficient synthesis of 3-aroylcinnolines starting from the appropriate aryl methyl ketones is described. The latter were converted in two steps to the corresponding 3-oxo-3-aryl-2-arylhydrazonopropanals, which upon acid catalyzed cyclization in conc. sulfuric acid or polyphosphoric acid (PPA) led to the corresponding 3-aroylcinnolines.

Efficient atom economic approaches towards macrocyclic crownamides via ring closure metathesis

RCM of suitable 1,ω-dienes led to efficient atom economic synthetic approaches towards azacrown ether derivatives with eight- to twenty four-membered ring sizes.

Efficient synthesis of 16-28 membered macrocyclic crown amides via ring closing metathesis

Abstract Ring closing metathesis of suitable diamides containing 1,ω-dienes led to efficient synthetic approaches towards macrocylic polyoxadiamides 1 – 18 with 16–28 membered ring sizes in good to excellent yields using Grubbs catalyst.

Flash vacuum pyrolysis of 3-aroylcinnolines: interesting routes toward polynuclear aromatic compounds

Abstract Flash vacuum pyrolysis of 3-aroylcinnolines 3 at 900°C and 0.02xa0Torr yielded phenanthrene and arylacetylene derivatives as the major products beside anthracene and diarylacetylene derivatives as minor products. Also, FVP of 3-(2-thienoyl)-cinnoline gave three isomeric naphthothiophenes, phenyl-2-thienylacetylene and phenylacetylene. On the other hand, 3-(2-furoyl)-cinoline gave dibenzofuran as a major product besides naphtho[1,2-b]furan and phenylacetylene.

Staudinger Ketene―Imine Cycloaddition, RCM Approach to Macrocrocyclic Bisazetidinones

Application of Staudinger ketene-imine cycloaddition reaction to bis-o-allyloxyarylideneamines afforded the corresponding bisallyloxyazetidinones as the cis-cis diastereomers, exclusively obtained as a mixture of cis-syn-cis and cis-anti-cis. RCM of the latter using Grubbs catalysts afforded the corresponding macrocyclic bisazetidinones in good yields. The cis-anti-cis bisazetidinones are readily identified by (1)H NMR using Eu(hfc)(3) chiral shift reagent.

Efficient highly stereoselective synthesis of olefinic macrocyclic crown-formazans with the Z-configuration via ring-closure metathesis

Abstract RCM of 1,5-bis- o -allyloxyphenylformazans with the suitably located 1,ω-dienes leads to an efficient, highly stereoselective, synthetic approach towards Z -olefinic 15-membered ring macrocyclic crown-formazans with potential applications. A novel reduction of pyridine N -oxides to pyridines by the action of Grubbs’ catalyst has been discovered.

Flash vacuum pyrolysis of 3-oxo-2-arylhydrazonopropanals and related derivatives

Abstract Flash vacuum pyrolysis (FVP) of 3-oxo-2-arylhydrazonopropanals at 500°C and 0.02xa0Torr yielded the corresponding derivatives of anilines, N -formylanilines, N -benzoylanilines and benzoylnitriles. Similar FVP of phenylhydrazonomalononitrile, phenylhydrazonoacetylacetone and phenylhydrazono ethyl cyanoacetate gave aniline in addition to N -cyanoaniline and 3,6-dicyano-1,4-diphenyl-1,2,4,5-tetrazine, acetanilide, N -methylacetanilide, pyruvonitrile and N -phenylurethane.

Enaminones in a multicomponent synthesis of 4-aryldihydropyridines for potential applications in photoinduced intramolecular electron-transfer systems

Summary An efficient three component reaction with enaminones, primary amines and aldehydes resulted in easy access to 1,4-dihydropyridines with different substituents at the 1-, 3-, 4- and 5-positions. Microwaves improved the reaction yield, reducing also considerably the reaction time and the amount of solvent used. Chiral primary amines gave chiral 1-substituted-1,4-dihydropyridines. The 4-(1-naphthyl) and 4-(phenanthren-9-yl)dihydropyridine derivatives exhibited an interesting photoluminescence behavior, which suggests their potential application as suitable photoinduced intramolecular electron-transfer systems.

Sequential Staudinger Ketene−Imine Cycloaddition, RCM Approach to Highly Rigid Macrocrocyclic Bisazetidinones

An efficient approach to highly rigid macrocyclic bisazetidinones with interesting structural feature was achieved via sequential Staudinger ketene-imine cycloaddition of o-allyloxyphenoxyketene and bis-arylidenediamines followed by RCM. The ketene-imine cycloaddition afforded the corresponding bis-o-allyloxyphenoxyazetidinones as the cis-cis diastereomers, exclusively obtained as a mixture of cis-syn-cis and cis-anti-cis. RCM of the latter using Grubbs catalysts afforded good yields of the corresponding novel macrocyclic bisazetidinones. The cis-anti-cis bisazetidinones are readily identified by (1)H NMR using Eu(hfc)(3) chiral shift reagent. (1)H NMR indicated the high shielding effect of the aryl substituents on one of the ortho-Hs of the condensed phenylene ring, and VT (1)H NMR indicates the highly restricted rotation of the aryl groups, thus offering a highly rigid system.

Sequential Staudinger ketene–imine cycloaddition, RCM approach to polycyclic macrocyclic bisazetidinones

An efficient approach to novel macrocyclic azacrown ethers incorporating two azetidinone rings fused to the macrocycle through the 3,4-positions of the azetidinone rings and two macrocycles fused at 1,3,4-positions of two azetidinone rings was achieved via sequential Staudinger ketene–imine cycloaddition of o-allyloxyphenoxyketene and bis-imines followed by RCM. The ketene–imine cycloaddition afforded the corresponding bis-o-allyloxyphenoxyazetidinones as the cis-cis diastereomers, exclusively obtained as a mixture of cis-syn-cis and cis-anti-cis diastereomers. RCM of the latter using Grubbs II catalyst afforded good yields of the corresponding novel macrocyclic bisazetidinones. Two cis-anti-cis bisazetidinones were readily identified by 1H NMR using Eu(hfc)3 chiral shift reagent and the structure of two macrocycles was established by X-ray crystallography.