338 



IV. WAXES, HIGHER ALCOHOLS, ETC. 



sidered to be the normal series while, those in which a tranf^ relationship 

 exists between these groups are referred to as the alio series. The struc- 

 tural relationship between the two series is illustrated in the diagrammatic 

 formulas for coprostane and cholestane. Bonds which are pictured as a 

 solid line project upward while interrupted lines extend in the opposite 

 direction : 



Coprostane 

 {A/B: cis-decalin type) 



(A/B: 



Cholestane 

 trans-dec-aAm type) 



In order to establish the position of the hydroxyl group on C3, it must be 

 related to some other group on the steroid nucleus. Ruzicka-"^ has chosen 

 the C5, which can serve only when the compound is saturated in the 5, 6 

 position. According to this scheme, cholesterol has a trans relationship at 

 these points, while the epi isomer possesses a cis relationship. This is 

 illustrated by the structural formulas assigned to dihydrocholesterol and 

 epi-dihydrocholesterol (only the A and B rings are included, since it is in 

 these rings that the differences exist). 



2"' L. Ruzicka, cited bj^ H. R. Rosenberg, Chemislrij and Physiology of the Vitamins, 

 Interscience, New York, 1945, p. 359. 



