A highly chemoselective reduction of aromatic and heteroaromatic nitro compounds

Reduction of aromatic and heteroaromatic nitro compounds to the corresponding amino compounds was achieved using tetrahydroxydiboron [B?(OH)?] [1] as the reductant and 4,4′-bipyridine as the organocatalyst, in DMF at room temperature, as outlined in Scheme below. [2]

This chemoselective reduction of aromatic and heteroaromatic nitro compounds under metal-free conditions is tolerant to various functional groups, such as vinyl, ethynyl, carbonyl, azide, nitrile and halogen. Preliminary mechanism investigations revealed that the H atoms in the amino function came from the tetrahydroxydiboron. In addition, a radical pathway was ruled out as a potential mechanism for this reduction process.

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[1] Around 80 €/25 g (MW: 89.65).

[2] M. Jang, T. Lim, B. Yong Park, M. S. Han, J. Org. Chem. 2022, 87, 910-919.