Osmium tetroxide, hydroxylation

C-Acyclic nucleoside analogs of inosine and guanosine 8-[(/ 5)-2,3-dihydroxypropyl]imidazo[l,5-fl]-l,3,5-triazin-4(3//)-ones were synthesized. The route involved the cyclization and rearrangement of 5-acylamino-5-allyl-6-amino-4,5-dihydropyrimidin-4-ones (1122) to 8-allylimidazo[l,5-a]-l,3,5-triazin-4(3//)-ones (1123). Osmium tetroxide hydroxylation gave 1124. None of these analogs showed appreciable antiviral or antitumor cell activity (84NAR263 87MI6). 

Osmium tetroxide hydroxylations can be highly enantioselective in the presence of chiral ligands. The most highly developed ligands are derived from the cinchona alkaloids dihydroquinine and dihydroquinidine.40 The most effective ligands are dimeric derivatives... 

The cis- 1,2-glycols, obtainable from the parent aromatic hydrocarbon by osmium tetroxide hydroxylation, can be converted to the corresponding trans-1,2-glycols by oxidation-reduction, using a mixture of dimethyl sulfoxide, sulfur trioxide, and pyridine, followed by lithium aluminum hydride reduction. The trans- 1,2-glycols can be dehydrated to arene oxides using DMF-DMA as mentioned above. Benzo[a]pyrene 4,5-oxide (28) and 7,12-dimethylbenz[a]anthracene 5,6-oxide (30) have been prepared by this method in 68 and 80% yields, respectively.18... 

The action of three oxidizing agents on the velbanamine component in vinblastine and related compounds has also been studied.1676 Osmium tetroxide hydroxylates the double bond between positions 15 and 20, if present, but also... 

A THC and other active constituents are believed to be metabolically converted to substances oxidized at C(7), and this oxidation has been carried out by osmium tetroxide hydroxylation of A THC (333) and subsequent removal of the tertiary hydroxy-group (Scheme 20). The isomerization of the double bond to A THC is most conveniently carried out by photo-isomerization in propan-2-ol and xylene for 14 days, " although a second method is available that depends on an El elimination reaction of the hydrogen chloride adduct of A THC, using a sterically hindered base (after blocking the phenolic hydroxy-group). ... 

Silylation of 276 with TBSOTf furnishes the bis-TBS ether, which undergoes an osmium tetroxide hydroxylation to afford the syn,anti,syn,anti,syn- iQi o 278 in 73% yield and with high diastereoselectivity. Selective diol oxidative cleavage with periodic acid, PCC oxidation of the resulting epimeric lactols to the lactone, followed by deprotection with /7-toluene-... 

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