Construction of multi-substituted pyrazoles <i>via</i> potassium carbonate-mediated [3 + 2] cycloaddition of <i>in situ</i> generated nitrile imines with cinnamic aldehydes
A highly efficient potassium carbonate-mediated [3 + 2] cycloaddition reaction of hydrazonoyl chlorides with cinnamic aldehydes to furnish multi-substituted pyrazoles under nontoxic and mild conditions has been developed.
Studies with enamines: Reactivity of<i>N,N</i>-dimethyl-<i>N</i>-[(<i>E</i>)-2-(4-nitrophenyl)-1-ethenyl]amine towards nitrilimine and aromatic diazonium salts
作者:Hamad M. Al-Matar、Sayed M. Riyadh、Mohamed H. Elnagdi
DOI:10.1002/jhet.5570440315
日期:2007.5
In the presence of triethylamine, cycloaddition reaction of enamine 1 with hydrazonoyl halides 2 followed by dimethylamine elimination was achieved, yielding the corresponding 1,3,4-trisubstituted pyrazoles 4. Coupling of enamine 1 with aromaticdiazoniumsalts afforded 2-(arylhydrazono)-2-(4-nitrophenyl)acetaldehyde 9 in good yield. Refluxing the phenyl hydrazone 9a with chloroacetone in ethanol in