Xylitol dianhydro

Until 1945 no anhydrides of xylitol or any other pentitol had been described. In that year a patent was granted to Grandel73 to make anhydrides of pentitols by heating them with a catalyst, followed by vacuum distillation. Xylitol on being heated with methionic acid followed by vacuum distillation gave monoanhydroxylitol and a dianhydro-(73) F. Grandel (to Alien Property Custodian), U. S. Pat. 2,375,915 (1945). 

The second dianhydro-xylitol was obtained23 by methylenation of 1,4-anhydro-DL-xylitol, with paraformaldehyde and concentrated hydrochloric acid, to give the 3,5-methylene acetal this was methylated to the 2-methyl ether, which was hydrolyzed, and the product mono-p-toluenesulfonylated to the 5-p-toluenesulfonic ester. On treatment with aqueous sodium hydroxide at 40-50°, the last gave syrupy l,4 3,5-dianhydro-2-0-methyl-DL-xylitol (17, D form). 

The n.mj. spectrum67 of dianhydro-xylitol23 and its methyl ether confirmed the chemical evidence that it has a 4-membered and a 5-membered ring, and hence is l,4 3,5-dianhydro-xylitol. This conclusion was further supported by the i.r. spectrum of the methyl ether, which has bands at 980 cm"1 (oxetane ring) and at 1050 cm"1 (oxolane ring).67... 

Danilov and coworkers79 treated l,4 3,5-dianhydro-DL-xylitol with a number of primary and secondary amines. The 3,5-anhydro ring was opened, to give the corresponding 5-amino-5-deoxy compounds. 

Pentadienone (divinyl ketone) was epoxidized55 by means of hydrogen peroxide in alkaline solution, to give a mixture of DL- and me.so-l,2 4,5-dianhydro-3-pentanones in the ratio of 13 7. Reduction of the ketone group in the DL-diepoxide with sodium horohvdride, followed by alkaline hydrolysis in dimethyl sulfoxide, was fully stereo-specific, and afforded DL-arabinitol. The same reaction-sequence performed on the meso-diepoxide led to a mixture of ribitol and xylitol. 

Loss of a second molecule of water occurs on heating (1) (106,107), (2), or (3) (108) with concentrated sulfuric or hydrochloric acid forming l,4 3,6-dianhydro-D-gludtol (isosorbide) (5). Mannitol and iditol anhydrize under similar conditions to isomannide (6) and isoidide (7), respectively. In (6), both hydroxyl groups are oriented toward each other (endo) in (7), both are oriented away from each other (exo) and in isosorbide (5), one hydroxyl is endo and the other exo. Xylitol loses two moles of water to form l,3 2,5-dianhydroxylitol (109). 

D-Glucitol hexanitrate256 and the pentanitrates of xylitol,257 ribitol,257 and L-arabinitol257 have been partially denitrated by the action of pyridine, but the structures of the reaction products were not ascertained. The dinitrates of the 1,4.3,6-dianhydro derivatives of D-mannitol, D-glucitol, and L-iditol react only slowly in anhydrous pyridine,258 and only traces of mononitrates could be detected in aqueous pyridine, mononitrates accounted for a maximum of 10% of the decomposed dinitrates. 

The configurations of a series of 2- and 5-substituted derivatives of 1,4 3,6-dianhydro-hexitols (4) have been established from their C n.m.r. spectra. Crystal structure measurements have shown thatl,5-anhydro-2,3,4-tri-0-benzoyl-xylitol and -ribitol both adopt the expected Ci(d) conformation, whereas l,2,3,4-tetra-0-benzoyl-/3-D-xylopyranoside adopts the alternative C4 form, emphasizing the importance of the anomeric effect in the latter case. Unsaturated alditol derivatives are mentioned in Chapter 12. 

In the pentitol series, xylitol on being heated with acids or with zinc chloride gives crystalline 1,4-anhydroxylitol and a sirupy dianhydro derivative, presumably with the 1,4 2,5-ring structure (6 ),... 

Alditols, Cyclitols and Derivatives Thereof. - 2,5 3,4-Dianhydro-D-altritol, 2,5-aohydro-3,4-0-(l,2-ethanediyl)-D mannitol, pentaerythritol tetraacetate, ribitol tetraacetate, xylitol tetraacetate, D-arabinitol tetraacetate, D, L-arabinitol tetraacetate, 2,4 3,5-di-0-isopropylidene-D-mannitol, 2 hexa-O-acetyl-D-mannitol, allitol hexaacetate, D-mannitol hexaacetate, D, L-mannitol hexaacetate, D-iditol hexaacetate, D, L-iditol hexaacetate, D, L-glucitol hexaacetate, D, L-altritol hexaacetate, L-galacto-D-galacto-decitol (which is C2-symmetric), 5 6-0-benzyl-2,3-0-[(S)-caniphanylidene]-l,4,5-tris-0-pivaloyl-D-myo-inositol, 6D-3,6-di-0-benzyl-l-0-[(S)-camphanyl]-2-deoxy-2,2-difluoro-4,5-0-isopropylidene- y< -inositol, cyclopentane 28. ... 

Unsaturated esters of 1,2 4,5-dianhydro-xylitol have been prepared the methacrylic ester reacted with lithium bromide to yield the... 

The properties, synthesis, stability, and metabolism of l,4 3,6-dianhydro-D-glucitol dinitrate have been discussed. The i.r. and Raman spectra of powdered 1,5-anhydro-xylitol, -ribitol, and -L-arabinitol have been reported Raman spectra were also recorded for solutions of the anhydro-sugars in water and in [ HeJDMSO. ... 

The preparation of some 2-acetamido-l,5-anhydro-2-deoxy-mannitol derivatives like (21) or (22) as potential inhibitors of sialic acid biosynthesis have been described. The conversion of xylitol into l,3 4,6-dianhydro-xylitol using anionic ruthenium iodocarbonyl complexes has appeared... 

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