Inositol, alio Inositols

It is to be noted that, in those inositols which have three axial hydroxyl groups, the two possible chair forms are equally stable. In the case of (unsubstituted) cis- and wiwco-inositol, the two chair conformations are super-imposable and are therefore indistinguishable. In alio-inositol, they are mirror images of each other aZZo-inositol is, therefore, an inseparable, racemic mixture of rotational isomers. Every hydroxyl group in cis-, muco-, and aZZo-inositol has an equal chance of being axial. 

Mehta G, Lakshminath S (2000) A norbornyl route to cyclohexitols stereoselective synthesis of conduritol-E, alio-inositol, MK 7607 and gabosines. Tetrahedron Lett 41 3509... 

Of the nine stereoisomers of inositol, the scyllo-isomer has no axial hydroxyl, the myo-isomer has one, the epi-, chiro-, and neo-isomers have two, and the alio-, cis-, and mneo-isomers have three hydroxyl groups (Figure 1). Of these, six isomers scyllo-, myo-, epi-, neo-, cis-, and mr/co-i somers) have one or more planes of symmetry in the molecule (meso compounds) and are therefore not chiral. D-chiro- and L-e/u>o-i somers do not have a plane of symmetry and are chiral molecules moreover they are enantiomers of each other. The alio-isomer is unique - the conformational isomer of (10) (Figure 2) is (11) which is also its enantiomer Since interconversion between conformational isomers is rapid, a//o-inositol exists as a 50/50 mixture of the two enantiomers at room temperature. Therefore, although alio-inositol is chiral, the compound is optically inactive at room temperature because it is a racemic mixture a chiral reagent, such as an enzyme, would be expected to preferentially react with one enantiomer and not the other. 

Similar reaction of the diacetal of neso-5,6-anhydro-alio-inositol (8) gave the dl(12345/6) trithiocarbonate (92), which has not been further investigated. ... 

Lee and Ballou111 investigated five liquid phases for the separation of inositol trimethylsilyl ethers and concluded that QF-1 gave the best results. This column packing permitted resolution of all but the myo-cis pair of inositols. They reported that the order of appearance, regardless of the stationary phase used, is alio, (neo, muco), racemic, (scyllo, epi), and (myo, cis). The order within the parentheses is sometimes reversed, depending on the liquid phase used. Wells and co-... 

A synthesis of the well-known natural products, the inositols, begins with a Diels-Alder reaction between furan and vinylene carbonate (73JOC117). Both the exo and endo oxabicyclo[2.2.1]hept-5-ene-2,3-diol carbonate adducts were obtained. fraus-Hydroxyla-tion of the endo adduct via the epoxide (33) afforded D-l,4-anhydroinositol (34). Hydrolysis of this compound with acetic acid and a small amount of sulfuric acid yielded alio- (35) and myo-inositol (36 Scheme 7). 

Kowarski, C R, Sarel, S, A total stereoselective synthesis of myo-, alio-, neo-, and epi-inositols,... 

There are nine various inositols or cyclohexane-1,2,3,4,5,6-hexaols, including one pair of isomers. The myo-inositol is the most widespread isomer of inositol and, excluding alio-, cis-, epi- and mwco-inositol, all other inositols are of natural occurrence. 

Well known alternatives to this fractional notation are based on the use of a set of eight prefixes alio, cis, dl, epi, muco, myo, neo, and scyllo) for the inositol configurations, and of ten prefixes alio, cis, epi, gala, muco, neo, proto, scyllo, talo, and vibo) for the quercitol configurations. Since these nomenclatures, due mainly to Fletcher, Anderson and Lardy, and... 

A route from furan-vinylene carbonate Diels-Alder adduct to inositols has been reinvestigated. Endo and exo isomers of oxabicyclo-[2,2,l]-hept-5-ene-2,3-diol carbonate (7) were separated and subjected to epoxidation or c -hydroxy-lation. Successive alkaline and acidic hydrolysis of epoxide 497, obtained from the endo adduct, produced a mixture of alio and myo inositols. cis-Hydroxylation of the endo adduct gave 1,4-anhydro-a//o-inositol 498, which afforded neo-inositol upon acidic hydrolysis. An analogous transformation of the exo adduct... 

The mass spectra of isomeric inositols do not show a molecular ion peak but the latter can be deduced from the presence of an M - - 1 peak at m/e 181 (21). Facile elimination of water gives rise to m/e 163. Judging from the relative intensity of this peak, the ease of elimination of water appears to be in the order neo > scyllo > alio > muco > levo > myo > epi > cis. 

Inositols are cyclohexanehexols that naturally occur as free, methylated, or phosphorylated forms. Of the nine possible isomers (Figure 2A), three are synthetic epi-, alio-, and ds-inositol), seven are optically inactive as meso forms, and two are enantio-morphs (d- and L-chiro inositol). However, phosphorylation or methylation of the inositol isomer most widely distributed in the nature, myo-inositol, at one of the hydroxyl groups 1, 3, 4, or 6 lead to chiral compounds, as shown in Figure 2B. Inositol... 

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