Stereocontrolled Total Syntheses of Optically Active Furofuran Lignans

Plant products (+)-sesamin, (+)-sesaminol, (+)-methylpiperitol, (+)-aschantin, and (+)-5'-hydroxymethylpiperitol were synthesized in a highly stereocontrolled manner through L-proline-catalyzed bifunctional-urea-accelerated cross-aldol reaction, followed by biomimetic construction of the furofuran lignan skeleton through a quinomethide intermediate.