The total synthesis of AB3217-A, a novel anti-mite substance, via intermolecular etherification and intramolecular glycosylation

The first total synthesis of AB3217-A has been achieved. The deacetylanisomycin unit, (3S,4S,5R)-3-benzyloxy-1-(benzyloxycarbonyl)-5-[(1R)-1-hydroxy-1-(4-me thoxyphenyl)methyl]-4-(2-tetrahydropyranyloxy)pyrrolidine (18), was prepared from dimethyl L-tartrate by a stereoselective pyrrolidine-ring formation and a stereoselective reduction of phenyl ketone as the key steps. The lithium alkoxide of 18 was coupled with the D-xylofuranose unit, phenyl-2,3-di-O-benzyl-5-O-trifluoromethanesulfonyl-1-thio-α-D-xylofu ranoside which was prepared from 1,2:5,6-di-O-isopropylidene-α-D-glucofuranose, via an intermolecular etherification. The resulting coupling product was subjected to de-O-tetrahydropyranylation and an intramolecular glycosylation to afford 4,12,13-tribenzyl-6-(benzyloxycarbonyl)AB3217-A (30). Final deprotection of 30 furnished AH3217-A.