A mass spectrometric criterion for determining the B- and E-ring hydroxylation pattern in dimeric biflavanoids

Abstract

Since only the ions with m/z corresponding to retro-Diels–Alder fragmentation products consisting of the original A-, B-, C-, and D-rings can be observed by the low-resolution mass spectra of the methyl ether diacetates of biflavanoids these ions can be used to determine the hydroxylation patterns of the B- and E-rings of unknown dimeric biflavanoids provided ¹H n.m.r. data are available as well.