Sasano Yusuke, Yamaichi Aoto, Sasaki Ryota, Nagasawa Shota, Iwabuchi Yoshiharu
Department of Organic Chemistry, Graduate School of Pharmaceutical Sciences, Tohoku University.
Chem Pharm Bull (Tokyo). 2021;69(5):488-497. doi: 10.1248/cpb.c21-00043.
Four distinctive sets of optimum nitroxyl radical/copper salt/additive catalyst combinations have been identified for accommodating the aerobic oxidation of various types of primary alcohols to their corresponding aldehydes. Interestingly, less nucleophilic catalysts exhibited higher catalytic activities for the oxidation of particular primary allylic and propargylic alcohols to give α,β-unsaturated aldehydes that function as competent Michael acceptors. The optimum conditions identified herein were successful in the oxidation of various types of primary alcohols, including unprotected amino alcohols and divalent-sulfur-containing alcohols in good-to-high yields. Moreover, N-protected alaninol, an inefficient substrate in the nitroxyl radical/copper-catalyzed aerobic oxidation, was oxidized in good yield. On the basis of the optimization results, a guideline for catalyst selection has been established.
已确定了四组独特的最佳硝酰基自由基/铜盐/添加剂催化剂组合，用于实现各种伯醇向其相应醛的有氧氧化。有趣的是，亲核性较弱的催化剂对特定的烯丙基伯醇和炔丙基伯醇氧化生成α,β-不饱和醛具有更高的催化活性，这些α,β-不饱和醛可作为有效的迈克尔受体。本文确定的最佳条件成功实现了各种伯醇的氧化，包括未保护的氨基醇和含二价硫的醇，产率良好至高。此外，N-保护的丙氨醇，这种在硝酰基自由基/铜催化的有氧氧化中效率较低的底物，也能以良好的产率被氧化。基于优化结果，已建立了催化剂选择指南。
