Isolation of the first C-2 addition products of anthocyanins

Addition of anthocyanins with nucleophilic agents normally occurs at the C-4 centre and the isolation of C-2 adducts between acetone and cyanidin-3- and delphinidin-3-rutinosides is the first definitive demonstration of the reactivity of this carbon site. These C-2 addition products were isolated as diastereoisomers and their chemical structures elucidated by 1D and 2D NMR spectroscopy.