Transition metal-catalyzed C−N bond formation using hydroxamic acid derivatives as the nitrogen source

Abstract

For the last decade, C−N bond formation from C−H bonds has been a powerful way of preparing value-added molecules that contain C−N bond. A wide range of nitrogen sources have been utilized in C−N bond formation protocols. Among them, this dissertation describes the applications of N-benzoyloxyamide in catalytic C−H functionalizations. First, an alternative acylnitrenoid precursors for $\gamma$-lactam synthesis was developed. Upon the action of Ir catalysis, N-benzoyloxyamides serve as efficient substrates to afford 5-membered amides via an intramolecular C−H insertion. Mechanistic studies revealed that the generation of a putative Ir-carbonylnitrenoid via N−O bond cleavage is facilitated by the chelation of counter cations. This protocol offers a convenient and step-economic route to $\gamma$-lactams starting from the corresponding carboxylic acids. Second, N-benzoyloxyamide as an amidyl radical source to form oxazoline was investigated. The use of radical species had required energetically demanding condition, making the control of reactions difficult. However, photocatalyst recently showed the possibility to control the radical reaction in benign environment, requiring only visible light as the main energy source. The resulting amidyl radical from N-benzoyloxyamide couples with styrene to form 1,2-aminoalcohol or oxazoline depending on the reaction conditions.