Abstract A novelseries of 1,1a‐dihydro‐1‐aryl‐2‐(3‐aryl‐sydnone‐4‐yl)‐azirino[1,2‐a] quinoxalines were prepared in a one‐pot reaction of 2,3‐dibromo‐1‐(3‐arylsydnone‐4‐yl‐)‐3‐arylpropan‐1‐one with o‐phenylenediamine employing triethylamine in ethanol. The new compounds were well characterized by IR,1H NMR, mass spectra, and C,H,N analysis.
The acidic decomposition of 4-acetylsydnonesarylhydrazones 2 results in the formation of 4-arylhydrazo-1,2-pyrazolin-5-ones 3 and 4-arylamino-1,2,3-triazoles 4, respectively. The reactions of 4-acetylsydnones 1 with arylhydrazines 5 afford compounds 3 as the only products in the absence of solvent.
A Concise Synthetic Method for Sydnonyl-Substituted Pyrazoline Derivatives
作者:Mei-Hsiu Shih
DOI:10.1055/s-2003-44357
日期:——
The pyrazolines have been found to have diverse applications in medicine. They are known to be potent antibiotic or antioxidizing agents. Two types of sydnonyl-substituted α,β-unsaturated ketones were synthesized by the Claisen-Schmidt condensation for the preparation of sydnonyl-substituted pyrazolines. One is the condensation of 3-(4-ethoxyphenyl)-4-formylsydnone (1) with acetone (2a) or acetophenone (2b), and the other is the condensation of 4-acetyl-3-arylsydnones 5 with various aryl aldehydes 6. Finally, 1H-pyrazoline derivatives 8 were synthesized successfully by reacting the appropriate α,β-unsaturated ketone precursors 7 with hydrazine hydrate.
1,3-Dibromo-5,5-dimethylhydantoin (DBH) as an efficient promoter for acetylation of 3-arylsydnones in the presence of acetic anhydride under neutral conditions
1,3-Dibromo-5,5-dimethylhydantoin (DBH) has been found to efficiently promote the conversion of various 3-arylsydnones to their 4-acetyl congeners in the presence of aceticanhydrideunderneutralconditions in satisfactory yields.
Friedel-Crafts acylations of various 3-arylsydnones at the C4 position have been achieved in good yields using 4 equivalents of an alkyl anhydride and 25 mol% each of bismuth triflate and lithium perchlorate in anhydrous acetonitrile at 95 degrees C. Acylations appear to be faster with arylsydnones bearing electron-donating moieties and sterically unencumbered anhydrides.