Of cyclitols

The replacement of the endocyclic oxygen of the sugar with a different element is another approach exploited to modify the anomeric reactivity. The carbon atom is the most obvious element to be used, the carbocycle so generated (cyclitol) completely loses the anomeric reactivity. The chemistry of cyclitols will not be described in this chapter as it is treated in another chapter of the same book. 

One of the efficient method for constructing carbohydrates is the Diels-Alder reaction, which gives a variety of important synthetic intermediates for the synthesis of cyclitol derivatives. We therefore were interested in the development of asymmetric Diels-Alder reaction by the use of chiral titanium reagents. 

In the United States a mixture of 60% cyclonite and 40% TNT was used under the name of Cyclitol as a filling for aerial bombs. The density of the cast explosive was 1.65-1.70, its rate of detonation 7800 m/sec, and in the ballistic pendulum it gave a value of 130 (100 for TNT). In the United States this mixture is considered to be only a little more sensitive to impact than TNT with a stability similar to that of cyclonite. This does not agree with T. Urbanski s [5] investigations according to which the sensitiveness to impact of such a mixture, in a powdered form, and its ignition temperature (225°C) approximate to the corresponding values for tetryl. 

Marsh, C. A. See Levvy, G. A. McCasland, G. E., Chemical and Physical Studies of Cyclitols Containing Four or Five Hydroxyl Groups, 20, 11-65... 

The stereospecificity of the oxidation of cyclitols and deoxycyclitols by Acetobacter suboxydans has been defined by Magasanik, Franzl and... 

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... 

The present review is to be regarded as a continuation of Fletcher s article1 the facts described therein will not be repeated here unless required for the understanding of recent developments. Because of the considerable expansion of cyclitol chemistry, it is not practicable to cover, as Fletcher did, all compounds of the cyclitol group. Only the inositols, the quercitols, and the inosamines, their derivatives, and some closely related compounds will be discussed the tetrahydroxycyclo-hexanes and -hexenes, and quinic and shikimic acids—on which subjects many important papers have appeared—are not reviewed here.3... 

The application of conformational analysis9 has been of considerable value in understanding some reactions of cyclitols it will, therefore, be... 

Further progress on the problem of the stereochemical specificity of cyclitol oxidation by A. suboxydans will depend on the isolation of the enzyme or enzymes involved. Cell-free preparations capable of oxidizing wn/o-inositol have been obtained,43 44 but these have not been further purified. The enzyme is apparently a true dehydrogenase, since it can couple with diaphorase.44... 

From the change of pH caused by successive additions of cyclitols to a borate solution, the equilibrium constants of complex formation have been calculated66 they show that the complexes are formed from cyclitol and borate in a 1 1 ratio. The stability of the tridentate borates depends on the steric disposition of the free hydroxyl groups in the complex the more of these in axial positions, the less stable the complex. This is illustrated by the values of the equilibrium constant in the following two series which are arranged by decreasing number of free axial hydroxyl groups in the complex scyWo-quercitol, 5.0 epf-quercitol, 310 m-quercitol, 7900 myoinositol, 25 epi-inositol, 700 and m-inositol, 1.1 X 106. When the constitution of a cyclitol allows the formation of both the tridentate and the classical, cis-1,2 type of complex, the former predominates. 

Electrophoresis on borate-buffered paper is potentially useful for the detection of cyclitols. So far, however, the principal application of this technique in the cyclitol field has been to studies on configuration and on the nature of cyclitol-borate complexes (see p. 153). 

The microbiological methods are all quite specific for free mj/o-inositol,98 and they can therefore be used for differential determination of free and bound inositol, as is often desired. But, because they are somewhat tedious, and not satisfactorily precise, many efforts to develop chemical methods have been made. The periodate reaction is the basis for most of these, although use of this reaction for the quantitative assay of cyclitols poses certain problems periodate reacts with almost all carbohydrates, and the reaction with cyclitols is, under the usual conditions, not stoichiometric (see p. 150). 

The recent reviews by Dangschat2(d) and Ballou2(e) have dealt extensively with cyclitols and related compounds in plants and micro-organisms. The emphasis in the following paragraphs is, therefore, on those aspects of the chemistry and biochemistry of the individual inositols which have not been discussed elsewhere. In particular, reports of the occurrence of cyclitols in plants are only included here if they are necessary for further discussion or if they are too recent to have been included in Dangschat s tables. 

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