Issue 47, 2021, Issue in Progress

Copper(ii)-catalyzed and acid-promoted highly regioselective oxidation of tautomerizable C(sp3)–H bonds adjacent to 3,4-dihydroisoquinolines using air (O2) as a clean oxidant

Abstract

A mild, efficient and eco-friendly method for the oxidation of 1-Bn-DHIQs to 1-Bz-DHIQs without concomitant excessive oxidation of 1-Bz-DHIQs to 1-Bz-IQs is very important for the syntheses of 1-Bz-DHIQ alkaloids and analogues. In this article, we developed a novel Cu(II)-catalyzed and acid-promoted highly regioselective oxidation of tautomerizable C(sp3)–H bonds adjacent to the C-1 positions of various 1-Bn-DHIQs. It was observed that when 0.2 equiv. of Cu(OAc)2·2H2O was used as the catalyst, 3.0 equiv. of AcOH was used as the additive and air (O2) was used as a clean oxidant, various 1-Bn-DHIQs could be efficiently oxidized to corresponding 1-Bz-DHIQs at 25 °C in DMSO. Especially, almost no concomitant excessive oxidation of 1-Bz-DHIQs to 1-Bz-IQs was observed during the above reaction. In addition, this method was successfully applied in the first total synthesis of the alkaloid canelillinoxine.

Graphical abstract: Copper(ii)-catalyzed and acid-promoted highly regioselective oxidation of tautomerizable C(sp3)–H bonds adjacent to 3,4-dihydroisoquinolines using air (O2) as a clean oxidant

Supplementary files

Article information

Article type
Paper
Submitted
24 Jul 2021
Accepted
30 Aug 2021
First published
06 Sep 2021
This article is Open Access
Creative Commons BY-NC license

RSC Adv., 2021,11, 29702-29710

Copper(II)-catalyzed and acid-promoted highly regioselective oxidation of tautomerizable C(sp3)–H bonds adjacent to 3,4-dihydroisoquinolines using air (O2) as a clean oxidant

Y. He, Y. Huang, Q. Fan, B. Zheng, Y. Luo, X. Zhu and X. Shi, RSC Adv., 2021, 11, 29702 DOI: 10.1039/D1RA05671A

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