Amino‐Acid‐Mediated Aerobic Oxidation of Organoborons for the Synthesis of Phenolic Derivatives Using Single Electron Transfer. Issue 8 (24th February 2020) - Gujjarappa, Raghuram
Abstract: An efficient amino‐acid‐mediated ipso ‐hydroxylation of arylboronic acids, aryl boronate esters and aryl trifluoroborates to aryl alcohols has been described. The current protocol was realized by using sub‐stoichiometric amount of l ‐histidine in presence of triethylamine under aerobic conditions in DMF as solvent. This amino‐acid‐mediated process provides an alternative route for the hydroxylation of organoborons through in situ generation of hydrogen peroxide. The present protocol explores the synthetic utility of amino acids as organocatalysts for the preparation of aryl alcohols. It was observed that l ‐histidine plays an important role for the conversion of aerial oxygen in to hydrogen peroxide via thermal excitation process followed by thermal degradation of Et3 N. The developed approach holds good for a wide range of compounds with excellent yields and competent functional group tolerance. Abstract : An easily accessible thermal‐induced oxidation of organoboron compounds has been described using l ‐histidine as a single electron transfer medium, triethylamine as an electron donor and aerial oxygen as an oxidant. This mild and amino‐acid‐mediated process was utilized to accomplish wide range of phenolic derivatives from various organoboron compounds.