Selective C3-H nitration of 2-sulfanilamidopyridines with tert-butyl nitrite

We report a selective C3-H nitration of 2-aminopyridines using the N-sulfonyl group as a directing group. This method provides access to a variety of C3 nitrated 2-sulfanilamidopyridine derivatives. The N-sulfonyl protecting group could also act as a good directing group for ortho-nitration of 3- and 4-aminopyridines. In addition, the late-stage selective nitration of corticosteroid 11-beta-dehydrogenase isozyme, secretory phospholipase A(2) inhibitor and human neutrophil elastase inhibitor was successfully achieved under the standard conditions.