Oligomeric flavanoids. Part 17. Absolute configurations of flavan-3-ols and 4-arylflavan-3-ols via the Mosher method

Abstract 1 H NMR analysis of R -(+)- and S -(−)-α-methoxy-α-trifluoromethylphenyl acetic acid (MTPA) esters of flavan-3-ols and 4-arylflavan-3-ols permits assessment of absolute configurations of C-3 of these condensed tannin structural units.