Anilines are found in pharmaceuticals, dyes, agrochemicals, and polymers. For the generation of ortho borylated anilines, outer-sphere directed iridium catalyzed C-H borylation (CHB) of N-(Boc)-anilines with B2pin2 (pin = pinacolate) is an effective method, albeit one that requires the installation and subsequent removal of the Boc group to afford the free aniline. The analogous CHB reaction of anilines with HBpin can also afford the ortho borylated products. These CHB’s proceed via the in situ formation of an ArNH-Bpin intermediate that directs the borylation ortho via a hydrogen bond interaction N-H...O between the hydrogen of the aniline and the Ir-Bpin catalyst. Substrate scope for both the NHBoc directed and the “traceless” ortho borylations is impacted and at times limited by the presence or absence of C-4 and/or C-6 substituents on the starting aniline. This presentation will describe recent successes at overcoming these substrate limitations, heighten ortho selectivity, and lower catalyst loadings.

Improved methods for ortho selective iridium catalyzed C-H borylations of anilines

256th National Meeting (2018)

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