A CONCISE SYNTHESIS OF THE METHYL-ESTERS OF (10S)-HEPOXILIN-B3 AND (10S)-TRIOXILIN-B3

2,3:4,5-Di-O-Isopropylidene-D-mannose was converted to lactol 2,3-O-isopropylidene-6(Z)-dodecene-L-ribofuranose (6) by Grignard addition with propargyl magnesium bromide, alkylation of the resulting terminal alkyne, partial hydrogenation of the triple bond, and finally chemoselective cleavage of the 1,2-O-isopropylidene and subsequent periodate cleavage of the glycol. Wittig olefination of 6 led to methyl 10(S),11(R)-O-isopropylidene-10,11,12(R)-trihydroxyeicosa-5,8,14(Z)-trienoate (5), which could be converted to (10S)-trioxilin B3 methyl ester (3) in one step or to (10S)-hepoxilin B3 methyl ester (4) in three steps.