Syntheses of polyfunctionalized resveratrol derivatives using Wittig and Heck protocols

Abstract

Improved protocols for Wittig reaction and palladium-catalyzed Heck coupling give expedient access to a series of unprecedented polyfunctionalized artificial-resveratrol derivatives. In the modified Wittig protocol, trimethylsilyl was used as a highly valuable protective group of the phenolic functions of starting aromatic materials. A clean O-alkylation of hydroxylated stilbenes with ethylene carbonate was also conducted. Thus, Wittig reaction followed by hydroxyethylation take place one-pot with only carbon dioxide as waste. Additionally, a palladium-catalyzed Heck coupling strategy was developed by using ferrocenyl phosphane ligands, and multi-functionalized hydroxylated stilbenes were obtained without the need of any protection/deprotection sequence. Up to six functional groups are introduced by these procedures, which limit the number of reactions steps, the waste toxicity, and the use of costly reagents.