Synthesis Of Isoxazolyl Substituted 1,2,4-Oxadiazolines And Pyrazolines And Microwave-Assisted Copper Catalyzed N-Arylation Of Imidazole

In the last decades, heterocycle compounds have been extensively studied by both organic synthetic chemists and medicinal chemists since a tremendous number of heterocycles have been proven to exhibit biological activities. In this thesis, we synthesized isoxazolyl substituted 1,2,4-oxadiazolines and pyrazolines as potential antibacterial agents, and developed a new method for the synthesis of N-arylimidazoles.1. 5-(tert-Butyldimethylsiloxylmethyl)-3-(1,5-diaryl-4,5-dihydropyrazol-3-yl)isoxaz oles were prepared from 3-acetyl-5-hydroxylmethylisoxazoles in three steps. The protocol gave products in excellent yields and the procedure is facile.2. 5-Methyl-5-[5-(tert-butyldimethylsiloxymethyl)-3-isoxazolyl]-3-aryl-4-(4-methyl oxyphenyl)-4,5-dihydro-1,2,4-oxadiazoles were synthesized via 1,3-dipolar cycloaddition of Schiff bases derived from 3-acetyl-5-hydroxymethyl-isoxazoles and nitrile oxides in situ generated from oximes. This one-pot protocol gave products in good yields and the procedure is very facile.3. A microwave-assisted synthesis of N-arylimidazoles was developed. The TV-arylation reaction between with imidazole and aryl halide in the presence of catalytic amount of Cul could be promoted efficiently by microwave irradiation. The reaction performed in DMSO without any ligant. Electron-rich group substituted aryl halides also gave good yields using this protocol.