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7670803 
Journal Article 
Total synthesis of ent-cholesterol via a steroid C,D-ring side-chain synthon 
Jiang, X; Covey, DF 
2002 
Yes 
Journal of Organic Chemistry
ISSN: 0022-3263
EISSN: 1520-6904 
AMER CHEMICAL SOC 
WASHINGTON 
67 
14 
4893-4900 
English 
12098302 
WOS:000176600400034 
For the first time, one of the two enantiomers of cholesterol (ent-cholesterol) has been synthesized by a synthetic route that starts from a precursor containing the D-ring and entire side chain of cholesterol. As part of the reported synthetic route, a method of general utility for the large scale (>10 g) preparation of each enantiomer of [1 alpha(R*),7a alpha]-1-(1,5-dimethylhexyl)-1,2,3,6,7,7a-hexahydro-7a-methyl-5H-inden-5-one, C,D ring-side chain synthons that can be used for the synthesis of enantiomers of vitamin D(3), cholesterol, and their analogues was also developed. Using the enantiomer of the C,D-ring side-chain synthon that leads to ent-cholesterol, the A- and B-rings were elaborated from a linear fragment that is sequentially cyclized to form the steroid B- and A-rings. Using this route, ent-cholesterol was prepared in 23 steps from the methyl ester of (1 alpha,5 alpha,6 alpha)-(+/-)-6-methyl-2-oxo-bicyclo[3.1.0]hexane-1-carboxylic acid in a total yield of 2.6%.