17a, 20a-Dihydroxycholesterol

It has been suggested that dehydroepiandrosterone can be formed directly from cholesterol, through either a 17a,20a-dihydroxycholesterol or 17a,20a,22-trihy-droxycholesterol. 

In another pathway, 17a,20a-dihydroxycholesterol. or 17a,20a-trihydroxycholesterol is an intermediate between cholesterol and dehydroepiandrosterone. Androgens are also assumed to be synthesized in liver and nongonadal tissue from 21-hydroxylated derivatives such as 3j8,17a,21 -trihydroxy-5a-pregnane-11,20-dione and 11-deoxycorticosol, which by splitting of the side chain yield dehydroepiandrosterone or androst-4-ene- 3,17-dione. 

C. Substituted Products - The introduction of an acetate group into the 7 xigl position has been accomplished by treating the 7-hydrazone with lead tetracetate. The stereochemistry of the addition reaction of Grignard reagents to 20-keto steroids was shown in the synthesis of 17a, 20a-dihydroxycholesterol. In such a manner C-27 side chain compounds, including one or more hydroxyl groups, could be synthesized. ... 

The synthesis and proof of structure for the two (C-20 isomeric) 17a,20a-dihydroxycholesterol and 17a,20/8-dihydroxy-20-isocholes-terol has been published by N. K. Chaudhuri et al. (1969). 

The two isomeric 17o ,20a-dihydroxycholesterol-7- H and 17a,20R-dihydroxy-20-isocholesterol-7- H were prepared by catalytic reduction of their respective 7-bromo-3-acetates (Burstein et al., 1968). 

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