Ruthenium(II)-Catalyzed Site-Selective Hydroxymethylation of Indolines with Paraformaldehyde

The facile synthesis of hydroxymethylated indole derivatives is crucial for their further development as pharmaceutical compounds and other synthetic purposes. Herein, we describe the ruthenium(II)-catalyzed hydroxymethylation of indolines and other N-heterocycles using paraformaldehyde as an abundant C1 feedstock. A wide substrate scope range and high levels of site selectivity as well as functional group tolerance were observed.