화학공학소재연구정보센터
Journal of the American Chemical Society, Vol.142, No.9, 4517-4524, 2020
Chemoselective Catalytic alpha-Oxidation of Carboxylic Acids: Iron/Alkali Metal Cooperative Redox Active Catalysis
We developed a chemoselective catalytic activation of carboxylic acid for a 1e(-) radical process. alpha-Oxidation of a variety of carboxylic acids, which preferentially undergo undesired decarboxylation under radical conditions, proceeded efficiently under the optimized conditions. Chemoselective enolization of carboxylic acid was also achieved even in the presence of more acidic carbonyls. Extensive mechanistic studies revealed that the cooperative actions of iron species and alkali metal ions derived from 4 angstrom molecular sieves substantially facilitated the enolization. For the first time, catalytic enolization of unprotected carboxylic acid was achieved without external addition of stoichiometric amounts of Bronsted base. The formed redox-active heterobimetallic enediolate efficiently coupled with free radical TEMPO, providing synthetically useful alpha-hydroxy and keto acid derivatives.