Catechin and epicatechin deprotonation followed by 13C NMR

The 13C NMR studies of catechin and epicatechin upon addition of base are reported. These flavan-3-ols show an interesting deprotonation behavior, dramatically different from the other type of flavonoids: catechin and epicatechin exhibit competitive deprotonation on B and A ring leading to a mixture of different monophenolates.