2019年7月24日

4,4’-Bipyridyl worked as an organocatalyst for reduction of nitroarenes by bis(neopentylglycolato)diboron (B2nep2) followed by hydrolysis to give the corresponding anilines. This reduction proceeded under aerobic conditions without any pre-purification of substrates and reagents. We found broad functional group tolerance for the substituents on the nitroarenes and compatibility for O- and N-protecting groups under the reaction conditions. The key in this catalytic system was the addition of B2nep2 to 4,4’-bipyridyl to form N,N’-bis[(neopentylglycolato)boryl]-4,4’-bipyridinylidene as a deoxygenating reagent of nitroarenes. Moreover, thermolysis of an intermediate N,O-bis{(neopentylglycolato)boryl}hydroxyaniline gave phenylnitrene that was trapped by B2nep2 in the catalytic system.

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