Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA.
Angew Chem Int Ed Engl. 2017 Jul 17;56(30):8892-8897. doi: 10.1002/anie.201704921. Epub 2017 Jun 21.
Electrocatalytic methods for organic synthesis could offer sustainable alternatives to traditional redox reactions, but strategies are needed to enhance the performance of molecular catalysts designed for this purpose. The synthesis of a pyrene-tethered TEMPO derivative (TEMPO=2,2,6,6-tetramethylpiperidinyl-N-oxyl) is described, which undergoes facile in situ noncovalent immobilization onto a carbon cloth electrode. Cyclic voltammetry and controlled potential electrolysis studies demonstrate that the immobilized catalyst exhibits much higher activity relative to 4-acetamido-TEMPO, an electronically similar homogeneous catalyst. In preparative electrolysis experiments with a series of alcohol substrates and the immobilized catalyst, turnover numbers and frequencies approach 2 000 and 4 000 h , respectively. The synthetic utility of the method is further demonstrated in the oxidation of a sterically hindered hydroxymethylpyrimidine precursor to the blockbuster drug, rosuvastatin.
电化学合成方法可为有机合成提供可持续的替代传统氧化还原反应的方法，但需要设计策略来提高专为这一目的而设计的分子催化剂的性能。描述了一种连接到芘的 TEMPO 衍生物（TEMPO=2,2,6,6-四甲基哌啶基-N-氧化物）的合成，该衍生物可在原位轻松进行非共价固定到碳纤维布电极上。循环伏安法和恒电位电解研究表明，与电子相似的均相催化剂 4-乙酰氨基-TEMPO 相比，固定化催化剂具有更高的活性。在一系列醇底物和固定化催化剂的制备性电解实验中，转化率数和频率分别接近 2000 和 4000 h-1。该方法的合成实用性在具有空间位阻的羟甲基嘧啶前体氧化为重磅炸弹药物罗苏伐他汀的反应中得到了进一步证明。
