TOTAL ASYMMETRIC-SYNTHESIS OF 3-DEOXY-HEXOSES AND 4-DEOXY-HEXOSES AND DERIVATIVES

(1S,4S)-7-Oxabicyclo[2.2.1]hept-5-en-2-one ((-)-5, a "naked sugar") has been converted to (-)-(1R,4S,6S)-6-endo-benzyloxy-2-bromo-7-oxabicyclo[2.2.1]hept-2-ene ((-)-12) in a highly stereoselective fashion. Double hydroxylation of the C=C double bond of (-)-12, followed by acetylation and Baeyer-Villiger oxidation of the resulting alpha-acetoxyketone (-)-14 afforded (-)-5-O-acetyl-2-O-benzyl-3-deoxy-beta-D-arabino-hexofuranurono-6,1-lactone ((-)-15). This compound was converted readily into (+)-methyl 3-deoxy-alpha-D-arabino-hexofuranoside ((+)-6) and (+)-methyl 3-deoxy-beta-L-xylo-hexofuranoside ((+)-7) and partially protected derivatives. (-)-15 was also converted into 4-deoxy-D-lyxo-hexopyranose (34) and several partially protected derivatives such as (+)-methyl 4-deoxy-2,3-O-isopropylidene-alpha-D-lyxo-hexo-pyranoside ((+)-8).