Herein we present a Pd-catalyzeddirectC–H hydroxylation of 2-arylpyridines using molecular oxygen (O2) as the sole oxidant. The key aspects of the method include: (a) the activation of molecular oxygen with a nontoxic and inexpensive aldehyde; (b) an efficient association of the in situ-generated acyl peroxo radical with palladium catalysis; and (c) convenient operating conditions. On the basis of
本文中,我们介绍了使用分子氧(O 2)作为唯一氧化剂的Pd催化2-芳基吡啶的直接C–H羟基化反应。该方法的关键方面包括:(a)用无毒且廉价的醛活化分子氧;(b)原位产生的酰基过氧自由基与钯催化的有效结合;(c)方便的操作条件。基于一系列对照实验中获得的结果,涉及Pd II / Pd IV催化循环的转化。此外,该方法可容易地以良好的分离产率获得广泛范围的取代的2-(吡啶-2-基)苯酚。
Regioselective synthesis of 2-(2-hydroxyaryl)pyridines from the reactions of benzynes with pyridine N-oxides
作者:Balagopal S. Shaibu、Rahul Kisan Kawade、Rai-Shung Liu
DOI:10.1039/c2ob26130h
日期:——
By modifying the conditions from those in Larock's reported synthesis of 3-(2-hydroxyaryl)pyridines from benzynes, and pyridine N-oxides, we altered the regioselectivity of the reaction toward an efficient synthesis of 2-substituted pyridines. The presence of ethyl propiolate altered the regioselectivity to afford 3-substituted pyridine products instead. We conducted appropriate control experiments
we report a new synthetic strategy for 2-(pyridin-2-yl)phenols and 2-(pyridin-2-yl)anilines catalyzed by a Pd/C–ethylene system. The starting materials, 2-(pyridin-2-yl)cyclohexan-1-ones, can be easily prepared by the reaction of substituted pyridine N-oxide and cyclohexanones. The most useful feature of this method is that both 2-(pyridin-2-yl)phenols and 2-(pyridin-2-yl)anilines are easily synthesized