10.1021/acscatal.0c01310
The research describes a novel method for the γ-C(sp3)–H oxygenation of free aliphatic amines, utilizing 2-hydroxynicotinaldehyde as a transient directing group and N-fluoro-2,4,6-trimethylpyridinium tetrafluoroborate as a bystanding oxidant. The purpose of this study was to develop a general protocol for the selective oxygenation at the γ-methyl positions of a wide range of aliphatic amines, which could be coupled with various aryl, heteroaryl, and aliphatic acids, as well as primary, secondary, and tertiary alcohols, to afford amine-containing esters and ethers. The conclusions highlight the method's broad applicability, good functional group tolerance, and its potential for late-stage functionalization of natural products and drug molecules, such as ibuprofen, isozepac, fenbufen, and lithocholic acid. This approach provides a more straightforward access to mono-protected amino alcohols and hindered ethers, which are challenging to synthesize using conventional methods.