Visible-Light Photocatalytic Synthesis of Amines from Imines via Transfer Hydrogenation Using Quantum Dots as Catalysts

Zi-Wei Xi; Lei Yang; Dan-Yan Wang; Chao-Dan Pu; Yong-Miao Shen; Chuan-De Wu; Xiao-Gang Peng

doi:10.1021/acs.joc.8b01651

Visible-Light Photocatalytic Synthesis of Amines from Imines via Transfer Hydrogenation Using Quantum Dots as Catalysts

J Org Chem. 2018 Oct 5;83(19):11886-11895. doi: 10.1021/acs.joc.8b01651. Epub 2018 Sep 13.

Authors

Zi-Wei Xi^{1

2}, Lei Yang¹, Dan-Yan Wang³, Chao-Dan Pu¹, Yong-Miao Shen^{1

2

3}, Chuan-De Wu¹, Xiao-Gang Peng¹

Affiliations

¹ Center for Chemistry of Novel & High-Performance Materials, Department of Chemistry , Zhejiang University , Hangzhou 310027 , PR China.
² School of Chemistry and Chemical Engineering , Shaoxing University , Shaoxing 312000 , PR China.
³ Department of Chemistry , Zhejiang Sci-Tech University , Hangzhou , Zhejiang 310018 , PR China.

PMID: 30168324
DOI: 10.1021/acs.joc.8b01651

Abstract

CdSe/CdS core/shell quantum dots (QDs) can be used as stable and highly active photoredox catalysts for efficient transfer hydrogenation of imines to amines with thiophenol as a hydrogen atom donor. This reaction proceeds via a proton-coupled electron transfer (PCET) from the QDs conduction band to the protonated imine followed by hydrogen atom transfer from the thiophenol to the α-aminoalkyl radical. This precious metal free transformation is easy to scale up and can be carried out by a one-pot protocol directly from aldehyde, amine, and thiophenol. Additional advantageous features of this protocol include a wide substrate scope, high yield of the amine products, extremely low catalyst loading (0.001 mol %), high turnover number (10⁵), and the mild reaction conditions of using visible light or sun light at room temperature in neutral media.