Researchers from the ZIOC developed a method for photocatalytic addition to the C = N bond

Reactions of radical addition to the carbon-nitrogen double bond are an important process that serves as a key step in many synthetic approaches and which, in some cases, opens the way to nitrogen-containing organic compounds that are difficult to obtain by other methods. With the development of the methodology of photoredox catalysis, which allows the generation of free radicals of various nature under mild conditions, the processes of radical addition began to attract even greater attention of researchers.

In the Laboratory of Functional Organic Compounds of the ZIOC it was found that chelate complexes resulting from N-acylhydrazones, boron trifluoride, and allylsilane were effective acceptors of alkyl radicals. Using this discovery, a process was developed for the synthesis of α-branched hydrazines by the reaction of these complexes with carboxylic acids under blue light irradiation. In the course of the reaction, alkyl radicals are generated from carboxylic acids, which are added to a multiple carbon-nitrogen bond. Presumably, the ability of a five-membered boron-containing ring to stabilize an intermediate radical is a key factor determining the efficiency of the reaction.

Source:

Igor A. Dmitriev, Vitalij V. Levin, Alexander D. Dilman Boron Chelates Derived from N‑Acylhydrazones as Radical Acceptors: Photocatalyzed Coupling of Hydrazones with Carboxylic Acids Org. Lett. 2021, 23, 8973–8977. DOI: 10.1021/acs.orglett.1c03501.