Rapid and Selective in situ Reduction of Pyridine-N-oxides with Tetrahydroxydiboron

Pyridine-N-oxides are often used as reactive precursors in the syntheses of substituted pyridines. Isolation and subsequent reduction of the associated pyridine-N-oxide intermediates can be challenging. We have discovered that tetrahydroxydiboron functions as a mild, versatile, and remarkably selective reducing agent for pyridine-N-oxides and may be used in an in situ fashion, thus obviating the isolation of N-oxide-containing intermediates