Steroids oxidation susceptibility

Steroids and sterols represent an important class of drugs that are susceptible to oxidative degradation through the possession of alkene moieties. The oxidation of phenothiazines forms the sulfoxide moiety. 

Enamines are susceptible to peracid oxidation, presumably through the epoxide, producing the a-hy-droxy ketone after hy lysis. Thus steroidal ketone (88) is converted via the pyrollidino enamine to the a-hydroxy derivative (89) in qiproximately 50% overall yield by treatment of the enamine with MCPBA followed by basic work up. Similar conversion of a steroidal enamide to the a>hydroxy ketone using monoperphthalic acid has been reported. 

The ability of the 11 -hydroxy-steroid (576) to undergo spontaneous oxidation to the 11-ketone in the pure crystalline state has been described.The reaction does not occur with the 21-alcohol or in the dark and is apparently unaffected by increased temperatures, unlike the closely related oxidation observed with crystalline hydrocortisone 21-t-butylacetate, which is temperature dependent and requires the presence of oxygen. The oxidation which also occurs with some other, but not all, esters of hydrocortisone seems to be dependent upon crystalline form, only those forms which solvate with non-stoicheiometric amounts of water being susceptible. 

Ganem has described a novel allylic alcohol to haloepoxide transformation (26) (28) using t-butylhypochlorite as the oxidant. This is the first known case where anchimeric participation by the hydroxyhalonium ion, as in (27), is invoked. The reaction, which has an analogy with iodolactonization, is susceptible to conformational and stereochemical requirements, since the octalin (29) gave a low yield of (30). Mild conditions for the preparation of (mostly steroidal) oxirans... 

In cases where ancillary substituents are less susceptible to oxidation, OSO4 can be replaced with alkaline KMn04, as exploited in the steroid series for examples such as carbon-14 labeled 7a-chloro-16a-methylprednisolone cinolone and dexamethasone (155) -... 

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