Synthesis of DL- and D-gluco-hept-3-ulose

DL-gluco-Hept-3-ulose was synthesised by oxidation of tri-O-isopropylidene-meso-glycero-gulo-heptitol with methyl sulphoxide-phosphorus pentaoxide, and subsequent hydrolysis. D-gluco-Hept-3-ulose (3) was synthesised by oxidation of one of the two isopropylidene derivatives from perseitol (D-glycero-D-galacto-heptitol), which is presumed to have the 2,2:4,5:6,7 structure, followed by hydrolysis. The crude product from the reduction of DL-gluco-hept-3-ulose with sodium borohydride showed two peaks corresponding to meso-glycero-gulo-heptitol and perseitol on g.l.c. of the trimethylsilyl derivatives. Isolation and acetylation of the latter heptitol revealed it to be racemic perseitol. Oxodation of DL-gluco-hept-3-ulose with oxygen in alkali followed by treatment with ferric acetate-hydrogen peroxide gave products with chromatographic behaviour characteristic of arabinonolactone and erythrose. Treatment of DL-gluco-hept-3-ulose with 2,4-dinitrophenylhydrazine gave a 1-deoxy-2,4-dinitrophenylosazone.