A4-Cholestene-3,6-dione

A4-Cholesten-3,6-dione is sensitive to air oxidation under certain conditions, particularly in alkaline solution. If the protective procedure specified is not followed the reaction product may be deep red and tarry. 

The residual solution contains a little cholesterol, 0.2-0.3 g. of A4-cholesten-3,6-dione, and small amounts of products derived from the oxidation of cholestanol and other companions. 

Mauthner and Suida 2 isolated, as one of three neutral products resulting from the oxidation of cholesterol with aqueous chromic acid in acetic acid solution, the substance later identified as A4-cholesten-3,6-dione. The present procedure is based upon results of a reinvestigation of the oxidation by a low-temperature, non-aqueous procedure.3... 

Reduction of enediones. A4-Cholestene-3,6-dione (1) is reduced by chromous chloride in either THF or acetone to 5/3-cholestanone-3,6-dione (2).3 Note that reduction with zinc and acetic acid gives the more stable 5a-cholestane-3,6-... 

Chlorotrifluoromethylcarbene, 223 N-Chlorourethane, 60, 61 AM-Cholestadiene-3,6-dione, 60 5a-Cliolestane-3,6-dione, 60 5oCholestane-2a , 3a-oxide, 135 5CfrCholestane-2j3,3(3-oxide, 135 5(3-Cholestanone-3,6-dione, 60 A4-Cholestene-3,6-dione, 60, 65 Al-5/3-Cholestene-3,6-dione, 60 A4-Cholestene-3-one, 98 A4-Cholestene-4-one, 60 -Cholestene-a-epoxide, 116 A5-Cholestenone, 65 Cholesteryl acetate, 35, 171 Cholesteryl acetate dibromide, 40 Chromic acid, 54, 246 Chromic anhydride, 54-57, 150 Chromic anhydride-Acetic acid, 56 Chromic anhydride-Dimethylformamide, 56 Chromic anhydride-Pyridine complex,... 

Oxygenation. Brackman et al.1 found that cupric acetate complexed with an amine (pyridine was used) in the presence of abase such as triethylamine functions as a homogeneous catalyst in methanol for the air oxidation of A5-cholestenone to A4-cholestene-3,6-dione in 75% yield. The reaction is applicable to a,fi- and fi.y-aldehydes and ketones for example ... 

Isomerization of a,(i-unsaturated ketones and esters. Schering chemists57 observed that 6)S-bromo-A4-cholestene-3-one (1) on reductive debromination with zinc in aqueous ethanol is converted into A -choleslene-3-onc (2), but that some isomerization to the conjugated ketone occurs simultaneously. However, it was possible to obtain the noncortjugated ketone in 25% yield. The cross-conjugated ketone 6/8-bromo-A1,4-androstadiene-3,17-dione (3) was converted into A1,r,-androstadiene-3,17-dione (4). 

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