Visible Light-Gated Organocatalysis Using a Ru-II-Photocage

[EN] The light-gated organocatalysis via the release of 4-N,N-dimethylaminopyridine (DMAP) by irradiation of the Ru(bpy)(2)(DMAP)(2)complex with visible light was investigated. As model reaction the acetylation of benzyl alcohols with acetic anhydride was chosen. The pre-catalyst releases one DMAP molecule on irradiation at wavelengths longer than 455 nm. The photochemical process was characterized by steady-state irradiation and ultrafast transient absorption spectroscopy. The latter enabled the observation of the(3)MLCT state and the spectral features of the penta-coordinated intermediate Ru(bpy)(2)(DMAP). The released DMAP catalyzes the acetylation of a wide range of benzyl alcohols with chemical yields of up to 99 %. Control experiments revealed unequivocally that it is the released DMAP which takes the role of the catalyst.

This is the peer reviewed version of the following article: J. A. González-Delgado, M. A. Romero, F. Boscá, J. F. Arteaga, U. Pischel, Chem. Eur. J. 2020, 26, 14229, which has been published in final form at https://doi.org/10.1002/chem.202001893. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.