Two new isomeric alpha-tetralones from Pyrola calliantha.

Abstract

Callianthones A ( 1) and B ( 2), a pair of new isomeric alpha-tetralones, together with a known alpha-tetralone ( 3) and four known flavonoids ( 4 - 7) were isolated from the 50 % EtOH extract of Pyrola calliantha. The structures and absolute configurations of the two new isomers were established to be (2 S,4 R) - and (2 S,4 S)-2,4-dihydroxy-2,7-dimethyl-3,4-dihydronaphthalen-1(2 H)-one ( 1 and 2, respectively) on the basis of spectral analysis, including 2 D NMR, model studies, and CD spectra.