Methods in synthesis of flavonoids. Part 3: Molybdenum(IV)-catalyzed coupling of cinnamyl alcohols to phenol derivatives

This paper deals with the formal total synthesis of flavonoids bearing the hydroxylation pattern of the catechin series based on an access to the fully functionalized skeleton via the alkylation of phloroglucinol tribenzyl ether by 3,4-dibenzyloxycinnamyl alcohol. This reaction was revealed to be most successful when catalyzed by the Mo(acac)2(SbF6)2 complex. In addition, the underlying concepts to the different ways that can be used in this C6–C3+C6 strategy are discussed.