Total Syntheses of (-)-Spirooliganones A and B and Their Diastereoisomers: Absolute Stereochemistry and Inhibitory Activity against Coxsackie Virus B3

To investigate the effects of configuration on bioactivity, spirooliganones A and B and their six diastereoisomers (1-8) were synthesized in 11 steps. The key benzopyran core was assembled by intermolecular [4 + 2] hetero-Diels-Alder cycloaddition between (-)-sabinene and o-quinone methide, which was generated from the corresponding o-hydroxybenzyl alcohol. After establishing the absolute configuration, the inhibitory activities of spirooliganones 1-8 against Coxsackie virus B3 were evaluated, and the primary structure-activity relationships were analyzed. Compound 3 was the most potent compound, with an IC50 of 0.41 mu M.