Furanose ring fragmentation

The oxidation of 1,2-O-isopropylidene-D-glucofuranose with lead tetraacetate was found by Criegee to yield formaldehyde,43 which confirmed the presence of a furanose ring in the sugar derivative. The major oxidation fragment, l,2-0-isopropylidene-5-oZde/q/do-D-a yZo-pentodialdose, was characterized subsequently by Iwadare,88 and has recently been shown to crys-... 

Figure 3-4. Overlay of symmetry-independent molecules in 4 by keeping the furanose ring as the fixed fragment (Cerius ). The C3—C5 boronate ester overlays nicely (left side) but the Cl—C2 portion has different orientations (right side). The orthorhombic form is shown in black and the two symmetry-independent molecules of the monoclinic form are shown in grey...

Fig. 9.13. Polar diagram of the puckering phase 0 (°) vs. the puckering amplitude (A) of 181 non-fused furanose rings in fragments of type 11 found in the CSD release July 1991 (no disorder, no error flag, i <0.08). The numbers show the position of some selected ring conformations 1(0°) envelope (e) with mirror plane through C(2 ) endo 2(144°) e C(3 ) endo 3(324°) e C(3 ) exo 4(180°) e C(2 ) exo 5(126°) twist with C2 axis through C(T) 6(72°) e O(l ) endo...

The 2,4-di-C-methyl-D-galactopyranose derivative (16) has been rearranged to the furanose isomer (17) and hence to the derivative (18)(Scheme 4) required for the synthesis of an erythronolide ring fragment. 

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