Aryllead triacetates as synthons for the synthesis of biflavonoids. Part 2. Synthesis of a Garcinia-type biflavonoid

Abstract

Arylation of 3-(phenylsulfonyl)chroman-4-one 1 with simple aryllead triacetates affords the corresponding 3-aryl-3-(phenylsulfonyl)chroman-4-one in 64–74% yield. However, no reaction took place with the hindered 2,4,6-trimethoxyphenyllead triacetate 9. Reaction of the 8-triacetoxyplumbylflavane derivative 10 with 4′-methoxy-3-(phenylsulfanyl)flavanone 11 afforded the biflavanone 12 in 64% yield. Nickel boride reduction of compound 12 led to the chalcone 13, which was recyclised to the Garcinia-type (I-3, II-8) biflavanone 14. Dimethyldioxirane oxidation of 12 gave the flavone-flavanone 15.