STEREOSELECTIVE CONVERSION OF D-GLUCURONOLACTONE INTO PSEUDO-SUGAR - SYNTHESES OF PSEUDO-ALPHA-D-GLUCOPYRANOSE, PSEUDO-BETA-D-GLUCOPYRANOSE, AND VALIDAMINE

Two optically active pseudo-sugars, pseudo-alpha-D-glucopyranose (12) and pseudo-beta-D-glucopyranose (13), were synthesized from D-glucuron olactone in favorable overall yields by using a stereoselective nitrom ethane addition reaction and a reductive elimination of an ethoxyethox yl moiety with NaBH4 as key steps. Furthermore, a biologically active pseudo-aminosugar, validamine (18) was efficiently synthesized via a s ubstitution reaction for an acetoxyl group at the beta-position of nit ro group in a nitrocyclitol derivative (14) which was prepared from a synthetic intermediate (9) of pseudo-D-glucopyranoses (12, 13).