330 INOSITOLS 



numbering proceeds in a clockwise direction. The multitude of possibilities 

 points to the unsatisfactoriness of this system, especially if inositol deriva- 

 tives are to be described. 



Magasanik and Chargaff^ proposed a system, which they applied to the 

 cyclohexitols and their keto and desoxy derivatives, in which the carbon 

 atoms are numbered clockwise, positions 1 and 6 chosen with their hy- 

 droxyls in trans position. The structure is arranged in such a manner as to 

 have as many hydroxyl groups as possible cis to the one in position 1. 

 Where this scheme allows two possibilities, that arrangement is chosen in 

 which the carbon atoms with hydroxyls cis to the one in position 1 have the 

 lowest positional numbers. The planar projection of meso-inositol would, 

 consequently, be numbered in the following manner. 



The inositol isomers are designated cyclohexanehexol, their desoxy deriv- 

 atives cyclohexanepentol, their monocarbonyl derivatives cyclohexane- 

 pentolone, the corresponding diketones cyclohexanetetroldione, etc. In the 

 case of the inositols it is sufficient to indicate the position of the cis hy- 

 droxyls. meso-Inositol is designated as cyclohexane-(l,2,3,5)as-hexoL 

 Similarly, its 2-keto derivative is described as cyclohexane-(l ,3,5)m- 

 pentol-2-one. The corresponding 2-desoxyinositol is cyclohexane-(l ,3,5)- 

 as-4,6-pentol. In this case the numbers of all hydroxyl groups must be 

 given. 



This system has the advantage that structures can be derived from 

 designations without reference to any visual aid. It leads, however, to 

 rather clumsy names, when sterically different polyfunctional derivatives 

 are to be described. Moreover, it requires enantiomorphs to be numbered 

 differently in equivalent positions. 



A scheme which avoids the last-mentioned disadvantage has been pro- 

 posed by Fletcher et al} (see the preceding section by Henry A. Lardy, 

 p. 323). 



B. PLANAR PROJECTIONS 



The planar projections of the cyclohexitols, including those not yet en- 

 countered or prepared, are shown in Table I. The structure of meso-inositol 

 (V) is based on the work of Dangschat and Fischer^ and Posternak''. The 



* B. Magasanik and E. Chargaff, J. Biol. Chem. 174, 173 (1948). 



B H. G. Fletcher, Jr., L. Anderson, and H. A. Lardy, /. Org. Chem. 16, 1238 (1951). 



* G. Dangschat, Naiurwissenschaften 30, 146 (1942). 

 7 T. Posternak, Helv. Chim. Acta 25, 746 (1942). 



