STRUCTURE OF PROVITAMINS D 751 



hydrocarbon w itli 7-mcth\ii)entenophenanthrene. This is a typical reduc- 

 tion product characteristic only of the sterols. On the basis of these reac- 

 tions and of others, ergosterol has been assigned the structure (I) shown 

 here. The above reaction involves the following changes. 



CHj 

 HjC C C \h f \ ^CH3 



i-yc; c c c hc 



HOv I I I "^ I ^CHj 



>v A /CH CH 



Hz H 



I 

 E rgoster ol 7-M ethylcy clopenteno- 



phenanthrene 



The close relationship of ergosterol (I) to cholesterol (VI) can readily be 

 demonstrated by its conversion to an acid common to both of the sterols 

 when the saturated hydrocarbons produced from the two sterols are oxidi- 

 zed. After ergostanol (II) is converted to ergostanyl chloride (III), it is 

 readily reduced to the saturated hydrocarbon ergostane, C28H50 (IV), by 

 reduction with sodium and am 3d alcohol. "^■'^° The latter hydrocarbon 

 can then be oxidized to a monocarboxylic acid, C23H38O2, which is identified 

 as nor-a/Zocholanic acid'^^ (V). This is the same acid as that obtained 

 from cholesterol (VI) after conversion to cholestane (VII). 



The formation of nor-allocholanic acid from ergostane and cholestane 

 indicates that the parent sterols have the same steric configuration. This 

 can also be assumed from the fact that both ergosterol and cholesterol are 

 precipitable with digitonin, indicating a jS-type of configuration for the 

 hydroxyl group. 



The data likewise indicate that the basic steroid nuclei of cholesterol and 

 of ergosterol are similar, and also that the first 5 carbon atoms on the side 

 chain are the same. Since ergosterol contains one more carbon atom than 

 does cholesterol, it is presumed that this must be in the side chain. The 

 fact that this is the case can be readily demonstrated by strenuous oxida- 

 tion of ergostanol (VIII) and cholestanol (IX) with chromic acid. After 

 such treatment, a ketone containing 9 carbon atoms (CgHisO) (X) is 

 obtained from ergostanol, while a corresponding compound with 8 carbon 

 atoms (CsHieO) (XI) is formed from cholestanol. ^^^ Further information 

 about the side chain of ergosterol is afforded by the reaction with ozone. 

 Under such conditions, methylisopropylacetaldehyde is formed. '^^•^■-•■' 



'" F. Reindel and E. Walter, Ann., 460, 212-224 (1928). 



120 .\. Windaus and W. Grosskopf, Z. physiol. Chem., 124, 8-14 (1923). 



'2' C. K. Chuang, Ann., 500, 270-281 (1933). 



'" .\. Guitera.s, Z. Xakamiya, and H. H. Inhoffen, Ann., 494, 116-126 (1932). 



'" F. Reindel and H. Kipphan, Ann., 4!)S, 181-190 (1932). 



