A Versatile Ru‐Catalyst for Selective Methylation of Diverse Organic Scaffolds Using Methanol as a C1 Synthon

Abstract Herein, we report an efficient Ru(III)‐catalyzed methylation of diverse organic scaffolds, including alcohols, ketones, nitroarenes, amines, indoles, naphthols, amides, and sulfonamides, using methanol as a green C1 synthon. A well‐defined, easy‐to‐prepare, bench‐stable Ru(III)‐catalyst featuring a redox‐active triamine ligand enables exceptional functional‐group compatibility and reactivity across multiple mechanistic pathways, including dehydrogenation, condensation, and (borrowing)‐hydrogenation. Unlike reported synthetic methodologies that require distinct catalysts for different substrate classes, our catalyst serves as a single, versatile system, eliminating the need for multiple catalysts while delivering high efficiency under mild conditions with reduced catalyst and base loading.