17a-Hydroxypregnanes

A 3-ketone in a 17a-hydroxypregnane-3,20-dione reacts selectively with acetone cyanohydrin to give the 3-cyanohydrin. This can be brominated at C-21 without affecting the A-ring, followed by removal of the protecting... 

An exploration of the electronic features of the D-homoannulation of 17a-hydroxypregnan-20-ones by boron trifluoride, in an attempt to account for the... 

Oximes, as their 0-methyl, 0-ethyl, or 0-trimethylsilyl derivatives, are useful for protection of pregnan-20-ones, including 17a-hydroxypregnan-20-ones, during gas chromatography the derivatives provide useful mass spectral patterns. 0-Methyl oximes at other positions have also been studied in detail. ... 

A 20-deoxy-17a-hydroxypregnan-21-oic acid failed to undergo lactonization, showing that the 20-OH is an essential feature for cyclization to occur. 

A17(20)-Olefin Formation via Favorski Rearrangement149 To a solution of 10 g of 3j3-hydroxypregn-5-en-20-one acetate in 200 ml of acetic acid is added 28.5 ml of a 1 M solution of bromine in acetic acid. After the addition of a few drops of 40% hydrobromic acid, an additional 57 ml of the bromine solution is added. Solid material starts precipitating upon addition of the last mole of bromine, and heating to 40° is necessary to cause complete reaction. The mixture is allowed to stand at room temperature for 2.5 hr, and the solid is filtered and washed with ether to give 15 g (63 %) of 5a,6/ ,17a, 21 -tetrabromo-3/ -hydroxypregnan-20-one acetate mp 172° (dec.). 

Cyanamide in methanolic ammonia converts 21-hydroxypregnan-20-ones (463) into 17j8-(2-amino-oxazol-4-yl)androstanes (464). The reaction proceeds equally well in the presence of a 17a-hydroxy-group. ... 

Chromous acetate, known to reduce 16a,17a-epoxypregnan-20-ones to give 16a-hydroxypregnan-20-ones. has now been employed for similar reductions of 4a.5a- and 4/3,5)S-epoxy-3-ketones (114), and also of a 6a,7a-epoxy-4-en-3-one (115). In each case the epoxide was selectively reduced at the bond nearest the carbonyl group, giving the 5a- or 5/3-hydroxy-3-ketone (116), and the 7a-hydroxy-4-en-3-one (117), respectively, in yields of about 50%. A neutral or buffered solution is required to minimize elimination, which occurs when acidic chromous chloride is used. 

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