A NOVEL-APPROACH TOWARDS CIS-FUSED AND TRANS-FUSED PYRANOPYRANS BASEDON RING-CLOSING METATHESIS REACTION OF CARBOHYDRATE-DERIVATIVES

A novel synthesis of both cis-and trans-fused pyranopyran systems, bas ed on ring-closing metathesis of glycal derived dienes, is described. Isomerisation of the resulting allylic double bond provides a new cycl ic enol ether, thus opening the way to an iterative synthesis of cis-( trans-)fused cyclic polyethers.