L,6-Anhydro-/3-D-glucopyranose

Es wurde gefunden, dafi, wenn im Molekul eine axiale Hydroxyl-gruppe an C-3 vorhanden ist, nur diese oxydiert wird. So bildet sich bei der katalytischen Oxydation von l,6-Anhydro- 3-D-glucopyranose (750), 1,6-Anhydro-p-D-galaktopyranose (752), 1,6-Anhydro-p-D-mannopyra-nose (756) und 1,6-Anhydro-p-D-talopyranose (760) in guten Ausbeuten... 

All of the crystalline pyranoses thus far examined adopt a chair conformation. A boat conformation has not yet been found for crystalline monocyclic compounds of sugars. Fused-ring systems seem to be required for part of the molecule to adopt a boat form, as in sedo-heptulosan (5) (where a chair form is also a part of a boat form (fused to the boat form)27 and l,6-anhydro-/3-D-glucopyranose. 

Jeffrey and Kim124 gave 3.30 A as the distance between the axially attached 0-2 and 0-4 in l,6-anhydro-/3-D-glucopyranose. This increased separation occurs, however, not only because nonbonded repulsion flattens the ring but also because of the formation of the anhydro ring. 

A few other examples may be found in related series. For instance, the methylenoxy bridge of l,6-anhydro-/3-D-glucopyranose can be cleaved, with subsequent bromination at both C-6 and the anomeric center.163... 

G. Procter, D. Genin, and S. Challenger, l,6-Anhydro-/3-D-glucopyranose in organic synthesis preparation of a fragment for the synthesis of rosaramycin, Carbohydr. Res., 202 (1990) 81-92. 

Hoschele62 has recently treated 6-0-trityl-/3-D-glucose tetraacetate with zinc chloride to form tri-0-acetyl-l,6-anhydro-/3-D-glucopyranose. The course of reaction undoubtedly was analogous to that described above for the formation of the latter substance from 1,2,3,4-tetra-0-acety 1-/3-d-glucose.33... 

The preparation of l,6-anhydro-/3-D-glucopyranose in quantitative yield by Karrer and Smirnoff,63 through the treatment of (tetra-O-acetyl-/3-D-glucopyranosyl)trimethylammonium bromide with aqueous alkali at 100°, in all probability proceeded by way of a mechanism analogous to that established by McCloskey and Coleman46 for the preparation start-... 

Evidence of complexing was obtained with the anomeric methyl 3,6-anhydro-D-glucopyranosides (see Table II), which suggests that the oxygen atoms on the pyranoid ring can play a role in ester stabilization (45) but, with l,6-anhydro-/3-D-glucopyranose (46), no complex was... 

At pH 10, diphenylborinic acid gives a tetrahedral anion that complexes with various diol systems, and thus it can be used in electrophoresis like borate.109 In a more detailed study of such complexing,110 diols were examined by 13C-n.m.r. spectroscopy, before and after addition of sodium diphenylborinate, and complexes were detected, and their spectra observed, for a variety of carbohydrate derivatives. 1,2-Diol groupings in acyclic and cis-cyclic compounds, 1,3-related diols at C-4,C-6 of hexopyranosides, the 3,5-diols of glucofuranoses, and 2,4-diols of the anomeric methyl 3,6-anhydro-D-glucopyranosides were all found to react. No interaction occurred with l,6-anhydro-/3-D-glucopyranose (compare Section V,2). 

Epoxides derived from l,6-anhydro-/3-D-glucopyranose undergo a rearrangement to generate allylic alcohols on treatment with MeLi and CuCN (e.g., Scheme 15) <2005EJ02841, 2005EJO4557>. 

Levoglucosan (l,6-anhydro-/3-D-glucopyranose) was first isolated and characterized as its triacetate and tribenzoate by Tanret, who obtained this compound through the treatment of natural phenolic D-glucosides (picein, salicin, and coniferin) with barium hydroxide. 

In the second approach to 1,6-anhydro sugars, anomeric esters, particularly glycosyl acetates, are activated by Lewis acids and displaced by labile ethers at 0-6. Rao has reported an efficient synthesis of tri-0-acetyl-l,6-anhydro-/3-D-glucopyranose by treatment of the trityl ether (4) with titanium chloride (O Scheme 3) [20]. 

As described earlier, treatment of methyl a-D-glucoside (5) with camphorsulfonic acid under Dean-Stark conditions yields a 7 1 mixture of l,6-anhydro-/3-D-glucopyranose (6)... 

A very similar equation had been previously derived from measurement of ip on l,6-anhydro-)3-D-glucopyranose, glycosides, and oligosaccharides in the solid state (Mulloy et al. 1988). 

Ammonolysis of l,6 3,4-dianhydro-2-0-benzyl-/3-D-galactopyran-ose (188) affords the 4-amino-4-deoxy derivative.740 It was also used for the preparation of the 2-amino-4-fluoro- and 4-amino-2-fluoro-2,4-dideoxy derivatives of l,6-anhydro-/3-D-glucopyranose.381 The oxirane ring of most dianhydrides is readily split not only by ammonia but also by its derivatives, such as methylamine, dimethylamine,320,7 7 and benzylamine.635... 

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