Synthesis Of The Derivatives Of D-Allofuranose

Withα-D-glucose (1) as starting material, ten D-allofuranose derivatives were prepared. Particularly, synthetic methods of cyclic carbonate, benzylation and 1,2-O-isopropylidene group selective hydrolysis were studied intensively.1,2:5,6-O-diisopropylidene-α-D-gluofuranose (2) was synthesized by isopropylidenation reaction fromα-D-gluofuranose. The yield was 50.1%. 1,2:5,6-O-diisopropylidene-α-D-allofuranose (3) was synthesized by PDC-Ac2O oxidation and NaBH4 reduction. Above two steps overall yield was 58.0%. Selective hydrolysis reaction was studied to synthesize 1,2-O-isopropylidene-α-D-allofuranose (4) with dilute solution of H2SO4 (0.5%). The yield was 94.0%.In the presence of a catalytic amount of sodium dicarbonate, ester exchange reaction was studied between compound 4 and diethyl carbonate. Thus 1,2-O-isopropylidene-α-D-allofuranose 5,6-carbonate (5) was synthesized with moderate yield (48.9%). 3-O-Acetyl-1,2-O-isopropylidene-α-D-allofuranose 8 was synthesized from 3 by acetylation and selective hydrolysis. Two steps overall yield was 86.3%. Bis(trichlormethyl)carbonate (triphosgene)was used to synthesize 3-O-acetyl-1,2-O- isopropylidene-α-D-allofuranose 5,6-carbonate(9) from compound 8 with high yield (93.2%). In the presence of a catalytic amount of 2,3-dichloro-5,6-dicynao-1,4-benzoquinone(DDQ), D-allofuranose 5,6-carbonate(6) and 3-acetyl-D-allofuranose 5,6-carbonate(10) were synthesized from compound 8 and 9 under different conditions in aqueous acetonitrile.3,5,6-Tri-O-benzyl-1,2-O-isopropylidene-α-D-allofuranose (11), 3,5,6-tri-O- chloroacetyl-1,2-O-isopropylidene-α-D-allofuranose (13) and 3,5,6-tri-O-acetyl-1,2 -O-isopropylidene-α-D-allofuranose (15) were synthesized from 4 by benzylation, chloroacetylation and acetylation, respectively. The yield was 71.6%, 94.7% and 92.3%, respectively. In the presence of a catalytic amount of 2,3-dichloro-5,6-dicynao -1,4-benzoquinone(DDQ), 3,5,6-tri-O-benzyl-D-allofuranose (12), 3,5,6-tri-O-chloro- acetyl-D-allofuranose (14) and 3,5,6-tri-O-acetyl-D-allofuranose (16) were synthesized from compound 11,13 and 15 under different conditions in aqueous acetonitrile. The yield was 82.7%, 67.6% and 65.7%, respectively. An alternative route was by 10% sulfuric acid hydrolysis from compound 11 to 12 with hige yield 87.4%.D-Allofuranose derivatives, 5,6 and 9-16,obtained in this paper were characterized by 1H-NMR spectra. Compounds, 5, 6, 9, 10, 13,14 and 16, were not been reported previously.