Synthesis of drynaran and analogues

Abstract

In a previous work, the natural compound drynaran, namely E-3-(5-hydroxymethyl)furan-2-yl)-2-phenylacrylaldehyde, was isolated from the Asian medicinal plant Drynaria bonii. Although this plant is used for several therapeutic purposes, drynaran was isolated in small quantities and, therefore, evaluated only for a few biological activities. Here, we propose a simple, fast, diastereoselective, and green synthesis of drynaran, using ethanol as solvent and 5-hydroxymethylfurfural as starting material. Drynaran was obtained in 66% yield and 98:2 E:Z diastereoisomeric ratio. The method was also used to produce a series of drynaran analogues, some of them as pure E-isomer and others in E:Z ratio of at least 90:10. Besides, five drynaran analogues formed crystals with suitable qualities for single-crystal X-ray diffraction data collection, and their crystal structures are described for the first time.