2, Northwestern University, Evanston, Illinois, United States
3, Korea Advanced Institute of Science and Technology, Daejeon, , Korea (the Republic of)
Porous organocatalysts offer confined spaces with tunable functionalities and a green alternative to precious metal catalysts. Imine formation is a key step in the synthesis of amino acids through amino nitriles. A simple and direct route is the oxidative self-coupling of amines. We recently showed that a novel and plausible mechanism that is based on catalytic, quantitative self-coupling of amines by air oxygen can produce substituted amino acid derivatives in excellent yields. The benzoxazole catalysts developed here provide quantitative catalytic activity over 50 cycles with favorable kinetics with no degradation. A time resolved spectroscopic monitoring rules out an aldehyde intermediate route in the imine formation. This work also marks the first use of benzoxazoles for oxidative catalytic reactions and provide new means and understanding for producing range of organic building blocks.