Pyrimidopteridine‐catalyzed Photo‐mediated Hydroacetoxylation

Abstract

Herein we report a photo‐mediated formal addition of carboxylic acids to activated alkenes catalyzed by a pyrimidopteridine photoredox catalyst. The decarboxylation of aliphatic carboxylic acids upon single‐electron oxidation is countered in the presence of electron‐rich alkenes and a hydroacetoxylation is observed. Mechanistic proposals have been made based on CV measurements, competitive Stern‐Volmer quenching and EPR experiments. Evidence that tetra‐N‐substituted pyrimidopteridines function as dual photoredox and hydrogen atom transfer catalyst was supported by spectroscopic means.

Addition of Carboxylic Acids to gem-Difluoroalkenes for the Synthesis of gem-Difluoromethylenated Compounds

“…Furthermore, substrates containing benzyl ( 2b ) and heteroaromatic ( 2c ) groups and even a trisubstituted difluoroacrylate ( 2d ) afforded the desired products in good yields. Regioselective addition of carboxylic acids to alkenes is not a trivial task, 8 and no examples of gem -difluoroalkenes are known to the best of our knowledge. We also screened other fluorinated and nonfluorinated alkenes under the same conditions for comparison, which were all unreactive ( Scheme 2 c).…”