Synthesizing Silyl Arylsulfonyl Hydrazones as Silyldiazomethane Precursors and Their Use in Rhodium‐Catalyzed Reactions

A method for synthesizing silyl arylsulfonyl hydrazones as silyldiazomethane precursors has been developed. Although silyldiazomethanes are an important class of diazo compounds, their use in intramolecular cyclization reactions has not been fully explored despite the rich chemistry of diazo compounds, particularly metal carbenoid chemistry. The fundamental challenge underlying the absence of such studies is the lack of a method for synthesizing silyldiazomethanes with functional groups that can react with metal carbenoids. The method reported here provides access to variety of silyl arylsulfonyl hydrazones with functional groups such as ethers, carbamates, and alkynes, which can serve as reaction sites for metal carbenoids. A one‐pot hydrazone formation using unstable formylsilane formed in situ is key to a successful synthesis. The use of 2,4,6‐trimethylbenzenesulfonohydrazide contributed toward achieving broad generality in hydrazone formation. The synthetic potential of this method was demonstrated through the generation of silyldiazomethane and its transformation to several silacycles.