Pseudo‐sugars, 30. Synthesis of Amino‐5a‐carba‐deoxyhexopyranoses from 2(3)‐Acetoxy‐5‐acetoxymethyl‐3(2)‐ p ‐toluenesulfonamido‐7‐oxabicyclo[2.2.1]heptanes

cis ‐Hydroxyamination of endo ‐2‐acetoxymethyl‐7‐oxabicyclo[2.2.1]hept‐5‐ene ( 1 ) under Sharpless conditions affords two positional isomers 3 and 7 of 5‐ endo ‐acetoxymethyl‐2(3)‐ exo ‐hydroxy‐3(2)‐ exo‐p ‐toluenesulfonamido‐ 7 ‐oxabicyclo[2.2.1]heptanes. Cleavage of the 1,4‐anhydro ring of the corresponding acetyl derivatives 4 and 8 with 18% hydrogen bromide in acetic acid at 80 ° C produces several bromodeoxy aminocyclitol derivatives, from which, on hydrolysis or nucleophilic substitution with an acetate ion, the known 2‐acet‐amido‐5a‐carba‐2‐deoxy‐α‐ DL ‐allo ( 25 ) and ‐gulopyranose tetraacetates ( 26 ), and new 3‐acetamido‐5a‐carba‐3‐deoxy‐α‐ DL ‐allopyranose tetraacetate ( 30 ) have been obtained. Likewise, the new 3‐acetamido‐5a‐carba‐3‐deoxy‐β‐ DL ‐talopyranose tetraacetate ( 39 ) has been prepared by starting from the exo ‐isomer 2 .