A New Synthesis of Stilbene Natural Product Piceatannol

摘要

Hydroxylated (E)-stilbene natural products are widely present in nature and show a variety of biological activities including anti-inflamatory, antioxidative, lipid-lowering, radical scavenging, neuroprotection, anticarcinogenic and antiviral activities. (E)-3,3',4,5'-tetrahydroxystilbene (piceatannol, 1, Figure 1) was isolated from Rheum undulatum which has been widely used in China and Korea for the treatment of blood platelet aggregation. It was reported that 0.3 g of pure piceatannol was isolated from 1 kg of dry root of Rheum undulatum. The limited supply of piceatannol from nature has prevented the diverse characterization of its biological activities. Several syntheses of (E)-stilbene have been reported by using Wittig-Horner, Heck and Suzuki coupling reactions. However, the polyhydroxy (E)-stilbenes are difficult to prepare due to oxidizing sensitivity of the polyphenolic groups, and due to inherent difficulties of controlling trans-selectivity. We report herein the new total synthesis of piceatannol (1) in 6 steps from vanillin by using Sonogashira coupling reaction.