First total synthesis of two nematicidal prenylated flavanones

The total synthesis of (±)-8-(3-methylbut-2-enyl)-2-phenyl-2,3-dihydrochromen-4-one and (±)-2-(4-hydroxyphenyl)-8-(3-methylbut-2-enyl)-2,3-dihydrochromen-4-one was first achieved through C-prenylation, protection of phenolic hydroxyl group aldol condensation, cyclization and deprotection starting from cheap benzaldehyde, 4-hydroxybenzaldehyde and 2-hydroxyacetophenone,with total yield of 20 and 16.3%. All structures of new compounds were confirmed by IR,¹H NMR and MS.