Three-Component Cascade Synthesis of Carbazoles through [1s,6s] Sigmatropic Shift under Metal-Free Conditions

A novel method was
developed for the synthesis of substituted carbazoles
from commercially available starting materials under metal-free conditions.
This strategy involves a [1s,6s] sigmatropic shift step and introduces
an electron-withdrawing ester substituent at the C2 position of the
carbazole ring. The present protocol afforded the desired carbazole
derivatives with good regioselectivity and well functional group tolerance.
DFT calculations were carried out to support the reaction pathway.