Molecular Iodine-Mediated α-C–H Oxidation of Pyrrolidines to N,O-Acetals: Synthesis of (±)-Preussin by Late-Stage 2,5-Difunctionalizations of Pyrrolidine,The Journal of Organic Chemistry

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Molecular Iodine-Mediated α-C–H Oxidation of Pyrrolidines to N,O-Acetals: Synthesis of (±)-Preussin by Late-Stage 2,5-Difunctionalizations of Pyrrolidine
The Journal of Organic Chemistry ( IF 3.3 ) Pub Date : 2017-05-12 00:00:00 , DOI: 10.1021/acs.joc.7b00361
Hao-Jie Rong ₁ , Jun-Jun Yao ₁ , Ji-Kun Li ₁ , Jin Qu ₁

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We previously reported an iterative synthesis of unsymmetrical 2,5-disubstituted pyrrolidines from pyrrolidine by two rounds of redox-triggered α-C–H functionalization. Although this approach can be used to introduce substituents at the 2- and 5-positions, it is lengthy because the redox auxiliary must be removed and then reinstalled. Therefore, we sought to develop a method to oxidize 2-functionalized pyrrolidine to cyclic N,O-acetal which could then react with a nucleophile for introduction of the 5-substituent. In this work, we found that molecular iodine can mediate the preferential oxidation of secondary over tertiary α-C–H bonds of α-substituted pyrrolidines to form cyclic N,O-acetals, improving the step economy of our previously reported method. With this strategy, (±)-preussin and its C(3) epimer were synthesized from (±)-pyrrolidin-3-ol.

中文翻译：

分子碘介导的吡咯烷的α-CH-H氧化为N，O-缩醛：吡咯烷的2,5-双官能团后期合成（±）-普鲁斯丁

我们先前报道了通过两轮氧化还原触发的α-C–H官能团由吡咯烷迭代合成不对称的2,5-二取代吡咯烷。尽管此方法可用于在2和5位引入取代基，但它很冗长，因为必须先去除氧化还原助剂然后重新安装。因此，我们寻求开发一种将2-官能化的吡咯烷氧化为环状N，O-乙缩醛的方法，其然后可以与亲核试剂反应以引入5-取代基。在这项工作中，我们发现分子碘可以介导α取代的吡咯烷的仲取代优先于叔α-C–H键的氧化，形成环N，O-缩醛，改善了我们先前报道的方法的步骤经济性。用这种策略，从（±）-吡咯烷丁-3-醇合成（±）-普鲁斯汀及其C（3）差向异构体。

更新日期：2017-05-19

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