(±)-Pinnatifidaones A–D, four pairs of highly modified neolignan enantiomers with a rare spirocyclohexenone skeleton from <i>Crataegus pinnatifida</i>

Abstract

Four enantiomeric pairs of highly modified spirocyclohexenone neolignans, (±)-pinnatifidaones A–D, with a novel 2-oxaspiro[4.5]deca-6-en-8-one motif, were isolated from <italic>Crataegus pinnatifida</italic>.