The nitrile oxide–isoxazoline approach to 11-carbon monosaccharides. Conversion of 3-(tetritol-1-yl)-5-(tetrofuranos-4-yl)-2-isoxazolines into 6-deoxyundecoses

Hydrogenolysis of (5R)-3-(1,2:3,4-di-O-isopropylidene-d-arabino-tetritol-1-yl)-5-(3-O-benzyl-1,2-O-isopropylidene-α-d-xylo-tetrofuranos-4-yl)-4,5-dihydroisoxazole afforded the 7-ulose derivative, from which 6-deoxy-d-gluco-d-gluco- and d-manno-d-gluco-undecose derivatives 17 and 18 were prepared by reduction with sodium borohydride or l-Selectride. The configuration of the new stereogenic centre (C-7) in compounds 17 and 18 was established by NMR analysis of their 5,7-O-isopropylidene derivatives. 6-Deoxy-l-manno-d-gluco- and l-gluco-d-gluco-undecose analogues 19 and 20 were prepared similarly from the isomeric 3-(l-arabino-tetritolyl)-4,5-dihydroisoxazole. Removal of the isopropylidene protecting groups from compounds 17 and 20 yielded 3-O-benzyl-6-deoxy-d-gluco- and l-manno-d-gluco-undecopyranoses, which were characterised as their octa-acetate derivatives. The corresponding reaction sequence from 3-(d- and l-arabino-tetritol-1-yl)-5-(2,3-O-isopropylidene-3-O-methyl-α-d-lyxo-tetrofuranos-4-yl)-4,5-dihydroisoxazoles afforded 6-deoxy-d/l-gluco-d-manno and d/l-manno-d-manno-undecose derivatives.