Stereoselektive epoxidierung von di-[3-O-(1,2:5,6-diisopropyliden)-α-D- und α-L-glucofuranosyl]-3,6-hexanooxepin-4,5-dicarboxylat

Abstract Epoxidation of the oxepine diester (−)- 1a leads to the oxirane (+)- 2a with ( S , S ) configuration in high yield. (+)- 1b on the other hand gives the (1a R ,6 R )-oxirane (−)- 2b . (+)- 2a undergoes photochemical ring closure to give (+)-( S , S , S , S )- 3a in 90% yield.