Maher R. Ibrahim

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.

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.

A direct synthetic approach to uracil anhydrothionucleoside derivatives.

Direct conversion of peracylated N(1)-(beta-D-glucopyranosyl)-2-thiouracil derivatives into the corresponding anhydrothionucleosides has been studied under various conditions including: gas-phase pyrolysis, heating without a solvent, and by heating in a solvent of high boiling point (DPE) in the presence of a base (DABCO) and reaction in a microwave reactor. Heating at 210-220 degrees C was found to give the best yield of a single isomer. The structures of the new anhydrothionucleosides were confirmed by NMR techniques.