The nucleophilic addition of methanol and other alcohols to 1,1-diphenylethylene (1) and styrene (6) into the Markovnikov- and anti-Markovnikov-type products was selectively achieved with 1-(N,N-dimethylamino)pyrene (Py) and 1,7-dicyanoperylene-3,4:9,10-tetracarboxylic acid bisimide (PDI) as photoredox catalysts. The regioselectivity was controlled by the photocatalyst. For the reductive mode towards the Markovnikov-type regioselectivity, Py was applied as photocatalyst and triethylamine as electron shuttle. This approach was also used for intramolecular additions. For the oxidative mode towards the anti-Markovnikov-type regioselectivety, PDI was applied together with Ph–SH as additive. Photocatalytic additions of a variety of alcohols gave the corresponding products in good to excellent yields. The proposed photocatalytic electron transfer mechanism was supported by detection of the PDI radical anion as key intermediate and by comparison of two intramolecular reactions with different electron density. Representative mesoflow reactor experiments allowed to significantly shorten the irradiation times and to use sunlight as “green” light source.

The synthesis of peptide-based photocatalysts that use 1-N,N-dimethylaminopyrene as chromophore and their application in photocatalysis is reported. The copper(I)-catalyzed alkyne-azide cycloaddition was applied as key step to prepare the peptide-pyrene conjugates in quantitative yields for different short peptide sequences. The photocatalysts were evaluated for the nucleophilic addition of methanol to 1,1-diphenylethylenes to products with Markovnikov-type orientation The short peptides contain arginine as substrate binding site during photocatalysis, and thus, the reaction was performed without the additive triethylamine that was previously applied as electron shuttle. Full conversion of the substrate and good yields for the addition product were achieved. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd.

Short proline‐rich peptides were synthesized and modified with 1‐(N,N‐dimethylamino)pyrene by copper(I)‐catalyzed cycloaddition. They perform photoredox catalysis of the nucleophilic addition of methanol to 1,1‐diphenylethylene derivatives into products with Markovnikov orientation. The common additive triethylamine is avoided because forward and backward electron transfer is controlled by substrate binding. A free carboxylic function in the substrate allows more precise substrate binding and defines the electron transfer path better than the unspecific exciplex formation with the substrate bearing a carboxylic ester. A proline‐type turn is an advantage for photoredox catalysis, but a proline‐induced helix is not required. This is the first successful example for introducing secondarily structured peptides to photoredox catalysis.

No abstract

In chemical photocatalysis, the photophysical process is coupled to a subsequent chemical reaction. The absorbed light energy contributes to the overall energy balance of the reaction and thereby increases its sustainability. Additionally, oligonucleotides and oligopeptides offer the possibility to control regio- and stereoselectivity as catalysts of organic reactions by providing potential substrate binding sites. We follow this path and want to explore how important substrate binding sites are for photocatalysis. The general concepts of photochemistry and biooligomer catalysis are combined for photochemically active DNAzymes for [2 + 2]-cycloadditions and proline-rich short peptides for nucleophilic additions to styrenes.