Cyclitols acetonation

Resolution of mixtures of cyclitols is more readily accomplished than is that of mixtures of sugar alcohols. Although the usual solvent developers are applicable, acetone-water mixtures61 can also be used. Ammoniacal silver nitrate27-61 or potassium permanganate serve as color reagents though neither is particularly sensitive.67... 

In contrast to the behavior of wn/o-inositol, other cyclitols and cyclitol methyl ethers are acetonated with ease, provided that they contain two contiguous, cis-hydroxyl groups. No reaction occurs with the (all-irons)... 

The usual sugar-reagents do not serve to detect cyclitol spots (except those of inososes). Ammoniacal silver nitrate has been widely used, but the best results90 are obtained with separate solutions of silver nitrate in acetone and sodium hydroxide in ethanol.91 The Scherer test has been adapted for use on paper chromatograms,91 and other reagents are useful in certain instances.89-90... 

Cyclohexylidene derivatives of 1,2-diob. Whereas 1,2-diols had traditionally been characterized by reaction with acetone to produce the acetonide or isopropylidene derivatives, Micovic and Stojiljkovic recommended conversion of sugars and other polyols into their cyclohexylidene derivatives because of the ease with which these substances crystallize. Angyal et al. explored the behavior of inositol (1) and found that this cyclitol gradually dissolved in a mixture of cyclohexanone and benzene containing p-toluenesulfonic acid on boiling under a Dean-Stark water separator. 

Isopropylidene derivatives. Various workers have reported difficulties in the preparation of 1,2-O-isopropylidenemyoinositol (1), probably because this cyclitol contains three contiguous c/r-hydroxyl groups. The reaction with acetone catalyzed by large amounts of zinc chloride is not complete after a reflux period of 50 hours.3 Ketal exchange with 2,2-diethoxypropane catalyzed by p-toluene-... 

It has often been assumed that any cyclitol having two cts-l,2-diol structures will react with acetone to give a diacetal. However, the dinitro-tetrol (106) affords only a monoacetal, for steric reasons. b. Diaminocyclohexanetetrols.— The dinitrotetrol (106), on reduction, gave the corresponding diaminotetrol. The conversion of dibromotetrols into diaminotetrols has been mentioned. Other methods include the reduction of a nitroaminotetrol derivative and of rhodizonic acid diimine (108). ... 

Cyclitols do not form alkylidene derivatives with the same ease as acyclic carbohydrates. However, the technique of Dangschat and Fischer, wherein zinc chloride catalysis is used, enables the formation of isopropylidene derivatives. They made brilliant use of this reaction in their elucidation of the structures of shikimic acid, quinic acid, conduritol, and mj/o-inositol (see above). The structures of the naturally occurring methyl ethers, pinitol and quebrachitol, were determined with the aid of this reaction (7, ISa, b), L-Inositol and cpi-inositol can be converted to triisopropylidene derivatives (7). This requires acetonation of trans hydroxyl groups. A chair conformation of the ring does allow vicinal trans hydroxyl groups in the equatorial plane to approach one another closely (7). 

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