Oxidation with osmium tetroxide

A solution of hydrogen peroxide in fer/-butyl alcohol is prepared by adding 400 mL of pure tert-butyl alcohol (free of isobutylene) to 100 mL of 30% hydrogen peroxide. The solution is treated with small portions of anhydrous sodium sulfate until two layers separate. The alcohol layer is removed and dried with anhydrous sodium sulfate and finally with anhydrous calcium sulfate (Drierite). The solution contains 6.3% of hydrogen peroxide in ferf-butyl alcohol. 

1 g (0.105 mol) of allyl alcohol is added 54.6 mL (0.1 mol) of 6.3% hydrogen peroxide in tert-butyl alcohol followed by 1 mL of a 0.5% solution of osmium tetroxide in tert-butyl alcohol. The reaction is exothermic and requires cooling with tap water. After 3 h, the reaction mixture is fractionated to remove the solvent, the catalyst, and the unreacted allyl alcohol (1.7 g). The residue is 4.2 g (60%) of glycerol. 

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Furo[3,2-c][l]benzopyran-4-ones have been prepared either by acid catalyzed condensation of 4-hydroxycoumarin with a benzoin derivative (equation 11) (81IJC(B)614) or from 3-allyl-4-hydroxycoumarins on oxidation with osmium tetroxide/potassium periodate followed by cyclization of the intermediary aldehyde with PPA (equation 12) (79G109). 

Lithium aluminium hydride reduction of 235 followed by mesylation afforded 236. The latter was oxidized with osmium tetroxide and sodium metaperiodate to yield the cyclobutanone 237. Treatment of 237 with acid afforded in 48% yield the ketoacid (238), which was esterified with diazomethane to 239. The latter was converted to the ketal 240 by treatment with ethylene glycol and /7-toluenesulfonic acid. Compound 240 was reduced with lithium aluminium hydride to the alcohol 241. This alcohol had been synthesized previously by Nagata and co-workers (164) by an entirely different route. The azide 242 was prepared in 80% yield by mesylation of 241 and treatment of the product with sodium azide. Lithium aluminium hydride reduction of 242 gave the primary amine, which was converted to the urethane 243 by treatment with ethyl chloroformate. The ketal group of 243 was removed by acidic hydrolysis and the resulting ketone was nitro-sated with N204 and sodium acetate. Decomposition of the nitrosourethane with sodium ethoxide in refluxing ethanol afforded the ketone 244 in 65% yield. The latter had been also synthesized previously by Japanese chemists (165). The ketone 244 was converted to the ketal 246 and the latter to 247... 

Vinyl and ethynyl groups attached to an imidazole ring can be catalytically reduced to the saturated (or less unsaturated) species and cleaved by oxidation. The corresponding 4-carbaldehyde is formed in 71% yield when l-methyl-2,5-diphenyl-4-styrylimidazole is oxidized with osmium tetroxide. However, they may not react like aliphatic alkenes and alkynes not all addition reactions occur normally, Michael additions are known, and the compounds can act as dienophiles in DielsAlder reactions (e.g., Scheme 132). 

A positional isomer of xylopinine of structure (345), prepared by synthesis, has been subjected to Hofmann degradation to the olefin (346), which on oxidation with osmium tetroxide gives the diol (347). Cleavage of the diol gave the dialdehyde (348), photolysis of which yields a mixture of cis-alpen-igenine (30%) and alpenigenine (339) (1%) (S.B. Prabhakar, et al., J.Chem.Soc., Perkin I 1981, 1273). The 7,8,13,14-tetra-... 

Reductive cyclization has been used in a novel, recent synthesis of the alkaloids ( )-isoretronecanol (22) and ( )-trachelanthamidine (23) by Borch and Ho. Condensation of the dianion derived from methyl acetoacetate with Z-l,4-dichlorobut-2-ene, followed by cyclization with sodium meth-oxide yielded the cycloheptenone ester intermediate (32) (Scheme 2). Reductive amination of this ketoester with sodium cyanoborohydride and ammonium nitrate gave a mixture of the diastereoisomeric aminoesters 33 and 34. Oxidation with osmium tetroxide and periodate, followed by reductive cyclization, again using sodium cyanoborohydride, gave the two pyrrolizidine esters 35 and 36 in a ratio of 1 2 [gas-liquid chromatography (GLC) analysis]. The esters were separated by preparative layer chromatography, and lithium aluminum hydride reduction of the individual esters gave the two pyrrolizidine alkaloids 22 and 23. 

In the extension of the reaction to polymers 1,2,4,5-cyclo-hexanetetrol was prepared in a 12% over-all yield from 1,4-cyclo-hexadiene by the oxidation with osmium tetroxide. The meso (12/45) diastereomer of (cis/cis) 1,2,4,5-tetrahydroxy-cyclo-hexane (15) was condensed with 1,4-cyclohexanedione to give a 95% yield of a crystalline spiro polymer VI. This material did not melt, but was soluble in hexafluoroisopropanol with an [r ] of 0.056 dl/g (25°, hexafluoroisopropanol). 

Although the spectroscopic data alone thus suffice for assignment of structure 15 (n=6, m=4) with some confidence, a single degradative experiment, oxidation with osmium tetroxide in the presence of sodium periodate provided rigorous confirmation, when -hexanal was identified among the products. 

To construct tricycHc compound 275, they first employed sodium boro-hydride to reduce the keto group to furnish alcohol 273. The terminal olefin was then converted to an alcohol via a two-step protocol employing oxidation with osmium tetroxide and sodium periodate followed by reduction with sodium borohydride to furnish diol 274, which underwent acid mediated lactonization. Dess—Martin oxidation of the remaining secondary alcohol then led to the desired tricyclic lactone 275. 

Oxidation specifically attacks thymine (57,58) and is applicable to all nucleic acid analytes. This strategy aims to either eliminate or alter thymine and thymine like-moieties for better analyte recognition. Oxidation with osmium tetroxide (5% OSO4) occurs at 300 pg/ml, with nucleic acids or DNA (plasmid) in 100 mM NaCl, 10 mM Tris (pH 7.6) and 1 mM EDTA. Incubation is at 70 C for 90 minutes. Standard ethanol extraction follows, with resuspension in tm-EDTA buffer. A series of chromatograms, including thymine altered by ozone and osmium are in press. 

The C-allyl jS-D-glucopyranoside tetra-acetate (60) has been converted into 4,5,6,8-tetra-0-acetyl-3,7-anhydro-D- /ycci 0-D- /o-octose (61) by sequential oxidations with osmium tetroxide and periodic acid. Compound (61) closely resembles a number of the C-glycosides referred to in Chapter 3. 

Oxidation with osmium tetroxide has been used as the basis for a method of determining bound butadiene in acrylonitrile - butadiene - styrene terpolymers. ... 

For the same reasons as described for the ozonolysis of alkenes, the oxidative cleavage of vicinal diols by periodate is hmited as a synthetic method. The vicinal diol is seldom directly available, and it must be prepared from an aUtene. We also recall that the hydroxyl groups must be located in a cis configuration, or the molecule must have sufficient conformational freedom to bring the two hydroxyl groups into a gauche conformation. The vicinal diol is prepared from an alkene by oxidation with osmium tetroxide. 

Dehydration of the tertiary alcohol (290) led to a miicture of approximately equal amounts of the A - and A -isomers (293) and (294) when it was oxidized with osmium tetroxide, all four theoretically possible isomers of the cis-diols (292) and (298) were obtained. At the same time, both in the case of the 16,17-diols (292) and in the case of the 17,17a-diols (298) the amount of the o -isomer was the greater. The cleavage of the first pair of diols (292) with periodic acid led to the ketoaldehyde (295), which, on being boiled in xylene with triethylammonium acetate, cyclized to form dl-5a-A -pregnen-3/S-ol-20-one acetate (296), identical in respect of its IR and UV spectra with the d-enantiomer obtained from natural sources. By a similar series of reactions, the second pair of diols (298) gave the keto-acetate (297) with an acetyl group at Cjg, isomeric with (296) [648, 649,... 

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