Yan-Qing Ge

Microwave‐Assisted Rapid and Straightforward Synthesis of Novel 6‐(Aroxymethyl)‐2‐aryl‐6,7‐dihydropyrazolo[5,1‐c][1,4]oxazin‐4‐one Derivatives

Abstract A series of novel 6‐(aroxymethyl)‐2‐aryl‐6,7‐dihydropyrazolo[5,1‐c][1,4] oxazin‐4‐one derivatives was synthesized from ethyl 3‐aryl‐1H‐pyrazole‐5‐carboxylate and 2‐aryloxymethylepoxide by a microwave‐assisted, one‐step method in good yields. The microwave‐assisted reaction of ethyl 3‐aryl‐1H‐pyrazole‐5‐carboxylate and 2‐aryloxymethylepoxide proceeds with higher regioselectivity and is more economical and environmentally friendly in contrast to the normal intramolecular esterification route. A tandem mechanism of the reaction was proposed.

Synthesis, X-ray crystal structure and optical properties of novel 2-aryl-3-ethoxycarbonyl-4-phenylpyrido[1,2-a]benzimidazoles.

A series of novel 2-aryl-3-ethoxycarbonyl-4-phenylpyrido[1,2-a]benzimidazole derivatives were synthesized by the tandem reaction of 2-benzoyl benzimidazole and (Z)-ethyl 4-bromo-3-arylbut-2-enoate in the presence of potassium carbonate. The compounds were characterized using IR, 1H-NMR, 13C-NMR, HRMS and the structure of 6f was further determined by X-ray crystallography. Both absorption and fluorescence spectra characteristics of the compounds were investigated in acetonitrile and dichloromethane. The results showed that the absorption maxima of the compounds varied from 220 to 284 nm, depending on the structure of 2-aryl group. The fluorescence results revealed that these compounds exhibited blue-green fluorescence (463-475 nm) in dilute solutions and showed acceptable fluorescence quantum yields (Ф(PL) = 0.13-0.73) in dichloromethane.

1-(2-Hydr­oxy-5-methoxy­phen­yl)ethan-1-one N-[(E)-1-(2-hydr­oxy-5-methoxy­phen­yl)ethyl­idene]hydrazone

In the title molecule, C18H20N2O4, which resides on a crystallographic centre of inversion (at the centre of the N—N bond), all non-H atoms apart from the methoxy substituent are approximately coplanar. The structure displays intramolecular O—H⋯N hydrogen bonding.

Ethyl 5-(ethoxy­carbon­yl)-3-(4-methoxy­phen­yl)-1H-pyrazole-1-acetate

In the title compound, C17H20N2O5, all bond lengths and angles show normal values. The dihedral angle between the pyrazole ring and the benzene ring is 6.98 (11)°. The molecules are linked by intermolecular C—H⋯π interactions.

Ethyl 1-[(6-chloro­pyridin-3-yl)meth­yl]-3-phenyl-1H-pyrazole-5-carboxyl­ate

In the title compound, C18H16ClN3O2, the dihedral angles made by the pyrazole ring with the pyridine and phenyl rings are 82.43 (2) and 8.16 (3)°, respectively. The crystal packing is stabilized mainly by van der Waals forces.

Ethyl 6-methyl-2-p-tolyl­pyrazolo[1,5-a]pyridine-5-carboxyl­ate

In the title molecule, C18H18N2O2, the bicyclic ring system and the benzene ring form a dihedral angle of 13.45 (3)°. In the crystal structure, weak intermolecular C—H⋯O hydrogen bonds link molecules into chains propagated along [201].

2-{5-[N-(4-tert-Butyl­benz­yl)carbamo­yl]-3-phenyl-1H-pyrazol-1-yl}acetic acid

In the title compound, C23H25N3O3, all bond lengths and angles show normal values. The dihedral angles between the rings of the pyrazole and the unsubstituted and tert-butyl-substituted benzene rings are 8.6 (2) and 78.5 (3)°, respectively, while that between the two benzene rings is 76.6 (3)°.