Skeletal Rearrangement of Indazoles to Indoles With α-Trifluoromethyl Diazosilanes.

Heterocycle interconversion represents a powerful strategy for molecular diversification. Despite its potential, the direct conversion of indazoles into indoles remains underdeveloped. Here, we report the first catalytic method for the direct transformation of indazoles to indoles, enabling the replacement of a single nitrogen atom with a trifluoromethyl-substituted carbon within a heteroaromatic framework. The reaction employs α-trifluoromethyldiazosilane as a carbene precursor and a copper catalyst, proceeding via N-N carbene insertion followed by a metal-free silyl-assisted rearrangement to achieve skeletal remodeling. This method features broad substrate scope, excellent functional group tolerance, and compatibility with complex drug molecules and gram-scale synthesis, offering a versatile platform for late-stage diversification.