Improved Procedure for the Enantiometric Synthesis of 1-Hydroxy/acetoxy-2,6-diaryl-3,7-dioxabicyclo[3.3.0] octane Lignans: Total Syntheses of (+)-Paulownin, (+)-Phrymarin I and (+)-Phrymarin II

Abstract

Short enantiomeric syntheses of the 1-hydroxy/acetoxy-3,7-dioxabicyclo[3.3.0]octane lignans, paulownin, and (+)-phrymarin I and II, were accomplished by starting from the chiral synthon, (R)-(+)-3-hydroxybutanolide, and employing photocyclization as the key step.