Reaction of α-Diazopyrroles with Enamines: Synthesis of Pyrrolo[2,1-c][1,2,4]triazines and α-(1,2,5-Triazapenta-1,3-dienyl)pyrroles

alpha-Diazopyrroles selectively react with enamines at room temperature to give either (4+2)-cycloaddition-dehydroamination cascade products, pyrrolo [2,1-c] [1,2,4]triazines, or azo coupling products. The reaction was used for the synthesis of functionalized ortho-fused heterocycles with new tetrahydrobenzo[e]pyrrolo[2,1-c][1,2,4]triazine and tetrahydro-6H-cyclohepta[e]pyrrolo[2,1-c][1,2,4]diazenyl]pyrroles, were obtained from enamines of tetralone or acyclic ketones. According to the density functional theory calculations, (4+2)cycloaddition of alpha-diazopyrroles with enamines proceeds in a nonconcerted manner via the zwitterionic intermediate, which undergoes cyclization to pyrrolotriazine or a competitive 1,5-prototropic shift leading to the formation of azo coupling product.

Automated summary

This study discovered that alpha-diazopyrroles selectively react with enamines at room temperature to produce organic compounds, which can be used for the synthesis of functionalized heterocycles.