3- a-Cholestanol

Chloroplast pigments 303 Chloropropham 108 Chloropropionic acid 45 Chlorothymol 67 a-Cholestanol 43,65 5-a-Cholestan-3-one 43, 334—336, 421, 422... 

To determine whether a more rigid conformation would increase the degree of selectivity of this remote oxidation, Breslow and Baldwin studied a similar system using the 3-a-cholestanol moiety,(77)... 

There are difficulties in the lack of an ideal internal standard for sterol determinations. Most used for this purpose are a-cholestanol (dihydrocholestanol), cholestane and betulin. Cholestanol is perhaps the most suitable where its resolution from cholesterol can be demonstrated. Cholestane and betulin, having none and two hydroxyl groups, respectively, do not migrate closely with the sterols on TLC and clearly their derivatization requirements do not match those of the analytes. 

The method is useful in the preparation of other axial alcohols. Henbest6 has reported the reductions of 3-bbutylcyclohexanone, 3,3,5-trimethylcyclohexanone, and cholestanone to the axial alcohols by this procedure, although for the preparation of 3 a-cholestanol the procedure of Edward7 is preferred by the checkers. Recently8 2,4,4-trimethylcyclohexanone has been reduced to the pure axial alcohol by this method in 90% yield. 

Hydrocarbons Bile acids Sapogenins N-Aryl-N, N -dialkyl-urea herbicides [79] [81,82] [84] [86] rooi Cholestanone, a-cholestanol Triterpene derivatives CycltAexanol Sulfur-containing polysaccharides [80] [83] [85] [87]... 

The terms a and are useful in describing the stereochemistry of steroid and carbohydrate systems. For steroid systems such as the isomers of 3-cholestanol in Figure 2.26, an a hydroxyl group is one that lies beneath the approximate molecular plane. ° ° Thus, 62 is 3-a-cholestanol. On the other hand, a /3 substituent lies above the approximate plane of the molecule, as shown by the structure of 3-j8-cholestanol (63). ° ... 

The ester of 3-a-cholestanol with p-iodophenylacetic acid held the iodine in such a position that an attached chlorine atom could reach the hydrogen of C-14, but not... 

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