Hexitols dianhydro

No authentic l,4 3,6-dianhydro derivatives of any other hexitols have yet been described (see however Table V). 

The ring system in these dianhydro hexitols is of interest and worthy of some discussion. The formula of isomannide (LXX) based on the Fischer projection formula for sugars does not convey the real character of the molecule and the author has chosen to write these substances as two fused tetrahydrofuran rings. Scale models show this to be a more exact representation. Thus isomannide is written as LXXI, isosorbide as LXXII, and L-isoidide as LXXIII. 

The stereochemistry of the hexitols affects the manner of ring fusion, as is seen in Figs. 3 and 4. In mannitol, sorbitol (gulitol) and iditol, the l,4 3,6-dianhydro rings are m-oriented, whereas in the dulcitol, allitol and altritol (talitol) series the 1,4 3,6-rings are trans-oriented. This makes the ring system in this latter series almost planar although in the case of dianhydrodulcitol and allitol there is considerable strain in the molecules. 

The most interesting ethylene oxide derivative of the hexitols encountered hitherto is 1,2 5,6-dianhydro-D-mannitol. This was obtained in the form of its 3,4-isopropylidene (LXXXVIII) and 3,4-ethylidene (LXXXIX) derivatives.72 The isopropylidene compound was synthesized from l,6-dichloro-l,6-didesoxy-D-mannitol through its conversion first into l,6-dichloro-l,6-didesoxy-3,4-isopropylidene-D-mannitol. This,... 

The hexitol anhydrides also have medicinal uses.97 Carr and Krantz98 found that l,4 3,6-dianhydro-D-mannitol was quite non-toxic to man and was a valuable diuretic. The dinitrates of both isomannide and isosorbide" have possible uses as agents for lowering blood pressure, though Burn and Stephenson100 found that the D-sorbitol derivative was twice as active as the D-mannitol derivative in this respect. 2,5-Diam-ino-2,5-didesoxy-l,4 3,6-dianhydro-D-mannitol and -D-sorbitol have been prepared and their sulfanilamido derivatives obtained.101 These however showed no outstanding bacteriostatic activity. 

One would also think that saccharides are more attractive starting raw materials for direct preparation of epoxy resins than hydrocarbons since they already possess oxygen atoms needed for the epoxy rings. Such diepoxy derivatives of hexitols are known compounds, for instance 1,2 5,6-dianhydro-3,4-0-isopropylidene-D-mannitol (XIX). Their preparation, however is difficult and requires 15 to 18 steps which proceed in very low overall yield (17-19). 

As a first step in this direction, we have been able to prepare 1,2 5,6-dianhydro-3,4-0-isopropylidene-D-mannitol as a model diepoxy hexitol derivative in four steps with overall 50% yield according to the following scheme ... 

Proton magnetic resonance spectra of the three l,4 3,6-dianhydro-hexitols and their diacetates and dimethanesulfonates were used in... 

After hydrogenolysis of l,6 2,3-dianhydro-4-0-benzyl- 3-D-mannopyranose over 10% Pd/C in ethanol, the reductive cleavage of an oxirane as well as of the 1,6-an-hydro ring has been observed to give I,5-anhydro-2-deoxy-D-ara6/ o-hexitol as the final product [223]. 

When two five-membered rings are cis fused, for example, as in l,4 3,6-dianhydro-hexitols, the common bridge atoms restrict the mobility of the individual atoms, and therefore only the combination of the two envelope conformations has to be considered (Figure 2.31). 

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. 

Anhydro-sugars - The dianhydro sugar 26, l,6-anhydro-4-0-benzyl-l-C-3-deoxy-isopropyl-2-0-methyl-D-r/6o-hexitoI and l,6-anhydro-4-0-benzyl-3-deoxy-2-0-4-C-dimethyl-D-r/Zjo-hexitoI, 1,5-anhydro-2,3-dideoxy-2-(guanin-9-yl)-D-flra6 o-hexitol, ° and 1,4-anhydro-D-glucitol and 1,5-anhydro-D-glucitol with a comparative discussion of the structures of these last two. ... 

A range of C2-symmetric cyclic 1,6- and 2,5-diamino-hexitols have been prepared as potential glycosidase inhibitors. Reaction of guanidine with the known bis-epoxides, l,2 5,6-dianhydro-3,4-0-isopropylidene-D-mannitol and -L-iditol, yields 21 and 22 respectively. The 2,5-diamino compounds 23 and 24 were derived from thiourea 25 by reaction with various amines, including methyl 6-amino-6-deoxy-a-D-glucopyranoside, in the presence of mercuric chloride. ... 

Another laboratory has reported the conversion of diacetone-L-glucose to a 3-deoxy-ribo-hexitol, and hence to the deoxy-arablno-hexitol (26), which could then be condensed with a similar polyol derived from (S)-malic acid to furnish the C-1—>C-12 unit in amphotericin B (27). The dianhydro-sugar (28) has been developed as a... 

Storbeck and Ballauff were the first to report on polyesters based on FDCA and dianhydro-hexitols [16]. Here, the acid chloride of FDCA was reacted with all three dianhydrohexitol isomers, in 1,1,2,2-tetrachloroethane in the presence of pyridine, giving white, fibrous polyesters. This work has been discussed in detail in the preceding section on isohexide polyesters (section 9.2.2). Later, Gandini and co-workers performed some kinetic studies on the transesterification of the FDCA dimethyl ester [66-68]. However, little attention was paid to polymer properties. More recently a series of papers on FDCA polyesters has been published by various groups, indicating the renewed interest in this subject. 

Noordover, B.A.J., Sablong, R.J., Duchateau, R. et al. (2008) Process for the production of a dianhydro-hexitol based polyester, W02008031592. 

Dianhydro-l-deoxy-4-0-mesyl-D-glucitol, D-492 2,5 3,6-Dianhydro-l-deoxy-4-0-tosyl-D-glucitol, D-492 1,2 3,4-Di-0 -benzylidene-5-deoxy-D-arabinitol, D-40 l,2-Dideoxy-am6mo-hexitol Y>-form, D-595 i>-erythro iorm, T-176 moM K) 2-Heptulose D-form 1-Deoxy, H-62 Methyl l-deoxy-D-r/6o-2-hexulopyranoside, D-222... 

The methyl, ethyl, and butyl ethers of the monoanhydro and dianhydro hexitols may be used as plasticizers 107). The diallyl and dimethallyl ethers of 1,4 3,6-dianhydro-D-glucitol slowly polymerize when in contact with oxygen 108). 

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