REACTIONS OF 3-DIAZO-1,3-DIHYDRO-2H-INDOL-2-ONE DERIVATIVES WITH ENAMINONES - A NOVEL SYNTHESIS OF 1,2,3-TRIAZOLES

A new and efficient method of 1,2,3-triazole synthesis is described in which these heterocyclics are formed through a novel nitrogen transfer from diazocarbonyl compounds to enaminones. Thus, the reaction of 3-diazo-1,3-dihydro-2H-indol-2-one derivatives 1 (X = NR3) and 3-diazobenzo[b]-thiophen-2(3H)-one 5 (X = S) with enaminones 2 and 7 leads to the formation of mainly 1,2,3-triazoles 4 and pyrazoloquinazolinones 3. Both the phenyl substituents (Y and Z in 1) and the nature of the X group affects the reaction rate and product distribution. Rate increases with an increase in the electron-withdrawing ability of the substituents Y and Z. The dinitro derivative 1g is shown to be the most efficient in promoting 1,2,3-triazole 4 formation while pyrazoloquinazolinones 3 are often competitively formed when other derivatives of 1 are employed.