Carboamination of olefins is an effective strategy to simultaneously create C-C and C-N bonds which are the most ubiquitous chemical bonds in nature. Directly converts simple olefins into various compounds including amines and amino acids, has attracted much attention.

However, general strategies for the carboamination of olefins with both intermolecular carbon and nitrogen sources have been less explored. Among the successful reports, carboamination with general alkyl groups remains an unsolved problem. This challenge can be attributed to the difficulty of initiating the reaction when using general alkylating reagents, such as alkyl halides.

In a study published in J. Am. Chem. Soc., the research team led by Prof. BAO Hongli from Fujian Institute of Research on the Structure of Matter of Chinese Academy of Sciences reported an iron-catalyzed intermolecular carboamination of olefins, using alkyl peroxides as alkylating reagents and nitriles as nitrogen sources. Various amines and unnatural anti-β-amino acid derivatives can be structured.

Researchers found that alkyl diacyl peroxides, readily synthesized from aliphatic acids, serve as both alkylating reagents and internal oxidizing agents. Benzylic amines and a-alkyl-β-aryl-β-amino acids are directly synthesized from simple olefins with moderate to good efficiency.

In particular, the β-amino acids are obtained with high diastereoselectivity, which will promote their further application in other fields. To exemplify a synthetic application of this method, analogues of a peptide opioid agonist (Tyr-Gly-Leu-Phe) were synthesized with the carboamination products replacing tyrosine.

A possible radical-polar crossover mechanism for the reaction is proposed via a sequence of radical addition, oxidation and a Ritter reaction. The two essential ingredients for this successful catalytic cycle are the alkylating reagents and metal catalyst.

Through isotope labeling experiments and a computational study, researchers revealed that addition of nitrile to the carbocation is the diastereoselectivity-determining step and hyperconjugation is proposed to account for the highly diastereoselective anti-carboamination.

This study is the first general alkylamination and diastereoselective alkylamination with trans-addition of carbon and nitrogen sources to double bonds.

This team has also reported decarboxylative alkyl etherification of olefins with general alkyl groups via iron catalysis. A variety of alkyl diacyl peroxides and peresters generated from aliphatic acids have been employed as alkylating reagents. This work was published in Angew. Chem. Int. Ed. 

The studies were supported by the National Natural Science Foundation of China, the 100 Talents Program and the 1000 Youth Talents Program.