Amines are widely used in pharmaceutical, agrochemical and materials chemistry. Reductive transformation of amides to amines is one of the most promising and straightforward methods for the synthesis of amines, as amides are naturally prevalent or easily accessed via chemical synthesis.
However, selective deoxygenative reduction of amides resulting from C–O bond cleavage is challenging. Catalytic hydroboration of C=O bonds has emerged as an efficient methodology to transform carbonyl compounds (ketones, aldehydes, esters, and carbon dioxide) into value-added products (normally O–B compounds without C-O bonds cleavage). However, catalytic deoxygenative hydroboration of carbonyls that resulted from C–O bond cleavage remains limited. Only few catalysts were successfully applied for such transformation. A general catalyst working for primary, secondary, and tertiary amides under mild condition is still limited. In addition, detection and isolation of reaction intermediate and detailed DFT calculations to understand the reaction pathway are lacking in the literature.
Recently, a research team led by Dr. Lipeng Wu from Lanzhou Institute of Chemical Physics (LICP) of the Chinese Academy of Sciences (CAS) and Prof. Haijun Jiao from LIKAT, Rostock, Germany reported an earth-abundant Zr-H catalyst for the effective amine synthesis. Meanwhile, detailed mechanistic studies revealed a distinct reaction pathway of aldehyde and amido complex formation via an unusual C-N bond cleavage-reforming and then C-O bond cleavage process. Extended application to the synthesis of bio- and drug-modified amines is also demonstrated. The results were published in Chinese Journal of Catalysis (DOI: 10.1016/S1872-2067(21)63853-6).
Source: http://english.dicp.cas.cn/