5,6-Unsaturated hexofuranosyl glycosides and 5′,6′-unsaturated hexofuranosyl nucleosides

Methyl 5,6-dideoxy-2,3-O-isopropylidene-alpha-D-lyxo-hex-5-enofuranoside, prepared from methyl 2,3-O-isopropylidene-5,6-di-O-methylsulfonyl-alpha-D-mannofuranoside with sodium iodide in 2-butanone, was acetolyzed and the product coupled with 6-benzamidochloromercuripurine by the titanium tetrachloride method. Removal of the N-benzoyl group with pictic acid afforded 9-(2,3-di-O-acetyl-5,6-dideoxy-beta-D-xylo-hex-5-enofuranosyl)adenine. In a similar manner, methyl 5,6-dideoxy-2,3-O-isopropylidene-alpha-L-lyxo-hex-5-enofuranoside was prepared from L-mannose and converted into 9-(2,3-di-O-acetyl-5,6-dideoxy-beta-L-xylo-hex-5-enofuranosyl)adenine, further de-esterified to give the free nucleoside. 2,3:5,6-Di-O-isopropylidene-alpha-L-mannofuranosyl chloride, prepared from L-mannose, gave 9-(2,3-O-isopropylidene-alpha-L-mannofuranosyl)adenine, hydrolyzed into 9-alpha-L-mannofuranosyladenine. Treatment with methanesulfonyl chloride gave the 5',6'-dimethanesulfonate, which gave with sodium iodide in acetone the 5',6'-unsaturated nucleoside, further hydrolyzed into 9-(5,6-dideoxy-alpha-L-lyxo-hex-5-enofuranosyl)adenine.