Organolead-mediated arylation of allyl β-keto esters: selective synthesis of 2′-hydroxyisoflavones

Abstract

Arylation of the A-ring-unsubstituted and -substituted 3-(allyloxycarbonyl)chroman-4-ones 6–8 with [4,5-dimethoxy-2-(methoxymethoxy)phenyl]lead(IV) triacetate 5 followed by selective catalytic deallyloxycarbonylation–dehydrogenation afforded 2′-protected isoflavones in high overall yields. Acid-catalysed removal of the methoxymethyl group led to the corresponding 2′-hydroxyisoflavones.