As waa demonstrated earlier, 1,2-alkylidene-& -D-glucofuranoeee react smoothly with hexaethyltriamide of phosphorous acid (HETPA), yielding bicyclophosphites exhibiting specific properties (1,2). It has become possible to extend this reaction to the series of hexafuranosides which contain four alcohol hydroxyls. As hae been shown, the formation of bicyclophoephites, in this case, ia strictly determined by etereochemietry of the monosaccharide. For example, S-ethyl-1-thio-D-glucofuranoaide (I) is converted to 3,5, 6-bicyclophoephite (II).
0.01 mole of (I) and 0.01 mole of HETPA are heated in pyridine (50 ml) at 90-100Β°C until no more diethylamine is liberated. The mixture is then evaporated in vacuum and chromatographed on Si02 (eluent ethyl acetate). Yield of (II) ii3 0.21 g (82%), m.p. 97-98OC, cdl p + 45O (C O,l, metbylene chloride); TLC on Si02: Rf C,81 (benzene: dioxan 3:l -A), 0.75 (ethyl acetate -B), 0.3 (chloroform -C). Found, %: C 38.8, H 5.0, P 12.2, calculated for C8H,305P. %: C 38.2, H 5.2, P 12.5. Amixture of d -(III) and 5 -ethyl-D-glucofuranosides-(IV) (0.01 mol), (3) and 0.01 mole of BETPA in pyridine (100 ml) is treated under the same conditions to afford a mixture of 3,5,6-bicyclophosphites (V) and (VI).
Chromatography on Si02 (A) reveals 1.16 g (60%) of (V), m.p. 121-122oC, 4125