Amino Acid-Catalyzed Cascade [3+2]-Cycloaddition/Hydrolysis Reactions Based on the Push-Pull Dienamine Platform: Synthesis of Highly Functionalized NH-1,2,3-Triazoles

The synthesis of NH-1,2,3-triazole products from simple starting materials through [3+2]-CA/H reactions under amino acid catalysis was investigated. The coupling of an organic azide with in situ generated push-pull dienamines led to protected 1.2.3-triazoles. Protected 1,2,3-triazoles were obtained under the standard reaction conditions. The amine or amino acid catalyzed cascade reaction was also investigated after successful demonstration of cascade EA/E and [3+2]-CA/H. A series of substituted Hagemann's esters were reacted with 0.5 equivalents of azides catalyzed by 20 mol% at 25°C in DMSO. It was observed that the cascade reactions proceeds in good yields with high selectivity using proline as the catalyst.