Electron and hydrogen transfer in organic photochemical reactions

• Published in: Journal of physical organic chemistry Vol. 28; no. 2; pp. 121 - 136
• Main Author: Hoffmann, Norbert
• Format: Journal Article
• Language: English
• Published: Bognor Regis Blackwell Publishing Ltd 01.02.2015; Wiley Subscription Services, Inc
• Subjects: heterogeneous photocatalysis; homogeneous photocatalysis; hydrogen abstraction; photochemical electron transfer; radical ions; radical reactions; stereo and regioselectivity; α,β‐unsaturated carbonyl compounds; β-unsaturated carbonyl compounds
• ISSN: 0894-3230; 1099-1395
• DOI: 10.1002/poc.3370

Electron and hydrogen transfers are basic steps in many chemical reactions. Photochemical or electronic excitation significantly influences the reactivity of chemical compounds and thus also these transfer processes. Furthermore, the formation of typical intermediates has a decisive impact on the outcome of the transformations. Based on these properties of photochemical processes, efficient homogeneous and heterogeneous photocatalytic transformations for application to organic synthesis have been developed. Efficient reactions without any chemical activation but induced by photochemical electron transfer can also be carried out. The photon acts as a traceless reagent. In the context of photochemical hydrogen transfer, two processes are frequently encountered. The two particles the electron and the proton are transferred either simultaneously or in two steps. In the latter case, the electron is transferred first and the proton follows. Both processes are applied to organic synthesis. Copyright © 2014 John Wiley & Sons, Ltd. Photochemically induced proton and electron transfers play an important role in many organic photochemical reactions. The way in which they are transferred has a significant influence on the outcome of these reactions. In this context, photochemical‐induced hydrogen transfer is described as a sequence of transfers of both particles.