中科院兰州化学物理研究所刘超团队报道了使用频哪醇硼烷三酰吡啶快速和可扩展地控制羧酸还原转化为醛。相关研究成果发表在2022年11月15日出版的《德国应用化学》。

建立控制羧酸转化为醛的新的有效方法是重要的。

该文中，研究人员报道了一种在环境温度下使用频哪醇硼烷将羧酸转化为醛的快速、模块化和可扩展的方法，其中使用三氟吡啶鎓试剂。三氟吡啶鎓将羧酸转化为中间体酰基吡啶鎓是一种新的方法。还原后生成二元吡啶配位硼络合物。HBpin史无前例地还原了酰基吡啶，开辟了从羧酸直接合成醛的新途径。

理论研究表明，酰吡啶的还原需要比产物醛更低的活化自由能。通过连续流工艺可扩展合成醛，进一步突出了该工艺的合成优势。手性酸的构型保留在这些合成过程中得到了体现。

附：英文原文

Title: Triflylpyridinium Enables Rapid and Scalable Controlled Reduction of Carboxylic Acids to Aldehydes using Pinacolborane

Author: Du Chen, Liangxuan Xu, Yi Yu, Qinliang Mo, Xiaotian Qi, Chao Liu

Issue&Volume: 2022-11-15

Abstract: Building up new and efficient method for the controlled conversion of carboxylic acids to aldehydes is important. Herein, we report a rapid, modular and scalable method for the conversion of carboxylic acids to aldehydes using pinacolborane at ambient temperature, in which a triflylpyridinium reagent is used. The conversion of carboxylic acid to intermediate acylpyridinium by triflylpyridinium is new. A binary pyridine-coordinated boronium complex is generated after reduction. The unprecedented reduction of the acylpyridinium by HBpin opens up a practically direct synthesis of aldehydes from carboxylic acids. Theoretical studies indicate that the reduction of acylpyridinium requires a lower activation free energy than that of the product aldehyde. The synthetic advantage of this protocol is further highlighted by the scalable synthesis of aldehyde via continuous flow process. Configuration retention for chiral acids are presented in those syntheses.

DOI: 10.1002/anie.202215168

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202215168