Bis oxygenation

The 17-ethylidene steroids are extremely useful intermediates for the preparation of 17-oxygenated, 20-oxygenated, or 17,20-bis-oxygenated pregnanes (Chart I) and their further conversion will be discussed in later sections... 

Many of the reactions already discussed for the preparation of bis-oxygenated pregnanes can also be used for the synthesis of 17,20,21-tris-oxygenated pregnanes by proper choice of substrate. Thus, reaction of a 17-vinyl-17-hydroxy steroid or a A -21-hydroxypregnene with osmium tetroxide will give the 17,20,21-triol, and the Stork reaction can be applied to 17a-hydroxy-20-keto steroids. 

Preparation of 17,20-bis-oxygenated pregnanes by side-chain oxygenation of pregnanes... 

The sequence was successfully applied to the synthesis of the phthalide isoquinoline hemiacetals (-)-egenine (6) and (-)-corytensine (7) from the bis-oxygenated precursor 513,14. 

In bismuth molybdates, the bridging Mo—O—Bi oxygen is the most weakly bound oxygen and therefore supposed to participate in the transfer of oxygen [219,281]. 

Figure 8(a)) (1) the bis-oxygenation of arachidonic acid (the cyclooxygenase activity or COX) forms PGG2 and (2) reduction of 15-hydroperoxide of PGG2 in the peroxidase (POX) active site to form PGH2. 

The temporary functionalization of cyclic or acyclic alkenes with a phenylsulfonyl group, followed by [4 -t- 2] cycloadditions of 1,3-bis-oxygenated dienes, opens a regiocontrolled route to annulated or 5-substituted cyclohexenones (Scheme 18). ... 

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