Osmium Tetraoxide Oxidation Research Articles

Structural Determination of Long Chain Bases of Ceramide Aminoethylphosphonate, Hemifusus ternatanus. I.

The dienic long-chain base (LCB), octadeca sphinga-4, 11-dienine was detected in ceramide aminoethylphosphonate (CAEP) from marine snail (Hemifusus ternatanus). To determine its structure. LCB was converted to various derivatives. The numbers of carbons and double bonds of LCB were determined by gas chromatography/mass spectrometry (GC/MS) of the trimethylsilyl (TMS) ether derivative and periodate oxidation product, an aldehyde. Double bond positions in the aliphatic chain were found by GC/MS of the TMS-polyhydroxy-N-acetyl derivative of LCB via osmium tetraoxide oxidation and the TMS-polyhydroxy-alcohol from LCB via periodate oxidation, followed by sodium borohydride reduction and osmium tetraoxide oxidation. Octadeca sphinga-4, 8-dienine were also shown present in CAEP from Hemifusus ternatanus based on the mass spectra of the TMS-polyhydroxy-N-acetyl derivative and TMS-polyhydroxy-alcohol.

Synthesis of 5,15-Diaryl-Substituted Oxochlorins from 5,15-Diaryloctaethylporphyrin

Abstract 5,15-Diaryl-substituted oxochlorins were prepared from osmium tetraoxide oxidation of 5,15-diaryloctaethylporphyrin followed by acid-catalyzed pinacol rearrangement. Optical and electrochemical properties of this macrocyclic ring are studied by measuring the absorption and fluorescence spectra, fluorescence lifetimes, and one-electron oxidation and reduction potentials.

ChemInform Abstract: Regiospecific Formation of 9,3‐Propeno‐8‐aza‐9H‐xanthines and Their Conversion into 3‐(2,3‐Dihydroxypropyl)‐8‐aza‐9H‐xanthine and Derivatives.

A novel series of C-11-functionalized 3,9-propano-8-aza-9H-xanthine and related compounds have been synthesized. With 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 11-methylsulphonyloxy-3,9-propano-8-aza-9H-xanthine (11) underwent a regiospecific elimination to give 9,3-propeno-8-aza-9H-xanthine (19). An equally interesting result was obtained from (19) on osmium tetraoxide oxidation, when 10,11-dihydroxy-3,9-propano-8-aza-9H-xanthine (20) was formed and then transformed into 3-(2,3-dihydroxypropyl)-8-aza-9H-xanthine (22) by aqueous NaBH4 treatment. Reaction of compound (19) with bromine in methanol afforded 11-bromo-10-methoxy-3,9-propano-8-aza-9H-xanthine (28). The latter on stereochemically controlled elimination with DBU led to 10-methoxy-3,9-propeno-8-aza-9H-xanthine (29), easily converted into 11-bromo-10,12-dimethoxy-3,9-propano-8-aza-9H-xanthine (30).

Regiospecific formation of 9,3-propeno-8-aza-9H-xanthines and their conversion into 3-(2,3-dihydroxypropyl)-8-aza-9H-xanthine and derivatives

A novel series of C-11-functionalized 3,9-propano-8-aza-9H-xanthine and related compounds have been synthesized. With 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 11-methylsulphonyloxy-3,9-propano-8-aza-9H-xanthine (11) underwent a regiospecific elimination to give 9,3-propeno-8-aza-9H-xanthine (19). An equally interesting result was obtained from (19) on osmium tetraoxide oxidation, when 10,11-dihydroxy-3,9-propano-8-aza-9H-xanthine (20) was formed and then transformed into 3-(2,3-dihydroxypropyl)-8-aza-9H-xanthine (22) by aqueous NaBH4 treatment. Reaction of compound (19) with bromine in methanol afforded 11-bromo-10-methoxy-3,9-propano-8-aza-9H-xanthine (28). The latter on stereochemically controlled elimination with DBU led to 10-methoxy-3,9-propeno-8-aza-9H-xanthine (29), easily converted into 11-bromo-10,12-dimethoxy-3,9-propano-8-aza-9H-xanthine (30).

Reactivities of Stable Rotamers. XXIII. Some Addition Reactions toward the Vinyl Group in 9-(2-Vinyl-1-naphthyl)fluorene Rotamers

Abstract Addition reactions to the vinyl group of the ap and the sp rotamers of 9-(2-vinyl-1-naphthyl)fluorene were carried out. Whereas action of sulfuric acid on the sp rotamer caused a cyclization reaction, the ap isomer was recovered under the conditions. While addition of bromine afforded normal products for both the isomers, reaction of chlorine afforded chlorine-substituted products (chloro olefins) in addition to the normal adduct, the formation of the former being predominant, in the sp form. The slightly enhanced reactivity of the sp form relative to the ap in bromination together with the formation of the chloro olefin and the behavior of the sp form in the treatment with sulfuric acid are attributed to the stabilization of the intermediates by the π-participation of the fluorene ring. Other addition reactions, epoxidation, hydrogenation, hydroboration, osmium tetraoxide oxidation, chlorination with (dichloroiodo)benzene, and diimide reduction, which are believed to proceed through a cyclic transition state, have also been studied to show that the rates of the reactions of one isomer are not much different from those of another. Spectroscopic data suggest that the conformation of the vinylnaphthalene portion in both isomers are similar. Little difference in the reaction rates of the two rotamers are attributed to the possible transition state conformation which may not be affected by the steric hindrance of the fluorene ring.

Syntheses of Optically Active Pentaacetates of Pseudo-β-l-allopyranose and Pseudo-α-d-mannopyranose

Abstract Diisobutylaluminium hydride reduction of d-glucose-derived chiral synthon, (1R,6R,8R,9R)-8,9-isopropylidenedioxy-7-oxabicyclo[4.3.0]non-4-en-3-one (1), gave a 7:1 mixture of (1R,3S,6R,8R,9R)- and (1R,3R,6R,8R,9R)-8,9-isopropylidenedioxy-7-oxabicyclo[4.3.0]non-4-en-3-ol, (2) and (2′). Introduction of cis-diol to the double bond of 3-O-acetyl derivatives of 2 and 2′ by osmium tetraoxide oxidation provided the diastereomeric mixture of (1R,3S,4R,5S,6S,8R,9R)-3-acetoxy-8,9-isopropylidenedioxy-7-oxabicyclo[4.3.0]nonane-4,5-diol (5) and (1R,3R,4S,5R,6S,8R,9R) diastereomer. Compound 5 was transformed to optically active pseudo-β-l-allopyranose effectively via (1R)-1-[(1S,2S,3S,4R,5S)-3,4,5-tris(benzyloxy)-2-hydroxycyclohexyl]-1,2-ethanediol (9). Cyclohexanecarbaldehyde formed by glycol cleavage of 9 was treated with methanesulfonyl chloride and reduced with lithium aluminium hydride to give (3S,4R,5S)-3,4,5-tris(benzyloxy)-1-cyclohexene-1-methanol (13). Compound 13 was efficiently converted to pseudo-α-d-mannopyranose pentaacetate by stereoselective hydroboration as a key reaction. The Wharton reaction of (1R,4S,5S,6S,8R,9R)-4,5-epoxy-8,9-isopropylidenedioxy-7-oxabicyclo[4.3.0]nonan-3-one derived from 1 gave(1R,5R,6S,8R,9R)-8,9-isopropylidenedioxy-7-oxabicyclo[4.3.0]non-3-en-5-ol, into which (3S,4S)-diol was stereoselectively introduced by oxidation with osmium tetraoxide.

Stereoselective total synthesis of (±)-isocelorbicol

A completely stereoselective total synthesis of the naturally occurring polyhydroxyagarofuran, (±)-isocelorbicol ( 1 ) is described. The readily available α-agarofuran derivative 3 was converted to 3β-hydroxy-9-keto-β-agarofuran ( 6 ) by epoxidation followed by rearrangement with strong base. Diimide reduction gave exclusively the required 4α-methyldihydroagarofuran ( 7 ), which was converted to the 2-dehydroagarofuran ( 8 ). Stereoselective LAH reduction and protection of the 9β-ol followed by epoxidation afforded 2β,3β-oxide 11 . This epoxide was converted to allylic alcohol 12 via reaction with phenylselenide and selenoxide elimination. Osmium tetraoxide oxidation of alcohol 12 gave exclusively the 1α,2α,3β-triol ( 13 ), which after protection as the acetonide, Barton deoxygenation and hydrolysis of the protecting groups afforded (±)-isocelorbicol. The overall yield for the 15 steps was 3.2%.

On stereochemistry of osmium tetraoxide oxidation of allylic alcohol systems. Empirical rule

An empirical formulation is presented to predict the stereochemistry of major osmylation products of allylic alcohols and their derivatives.

ChemInform Abstract: PSEUDO‐SUGARS. IX. SYNTHESIS OF THREE (HYDROXYMETHYL)CYCLOHEXANEPENTOLS

AbstractOsO4‐Oxidation des Cyclohexens (I) gibt ein Gemisch der Benzoate (IIa)+(IIIa), die durch Verseifung (mit methanolischem Na‐methylat) und nachfolgende Acetylierung die Hexaacetate (IIb) bzw. (IIIb) liefern.

Pseudo-sugars. IX. Synthesis of Three (Hydroxymethyl)cyclohexanepentols

Abstract Three new Dl-(hydroxymethyl)cyclohexanepentols, of which configurations are related to biologically important chiro- and myo-inositols, have been synthesized as hexaacetates from Dl-tri-O-acetyl-(1,3/2,4)-4-benzoyloxymethyl-5-cyclohexene-1,2,3-triol by osmium tetraoxide-oxidation or peroxy acid-oxidation followed by acid hydrolysis, and their structures have been established by 1H NMR spectroscopy.

Additional reactions of levoglucosenone

Several new, [4 + 2] cycloaddition products of levoglucosenone have been synthesized, and the oxidation of products of this type has been accomplished by several methods, including epoxidation and osmium tetraoxide oxidation, producing interesting polycyclic molecules. Additions of long-chain hydrocarbons to levoglucosenone have also been investigated via Grignard reactions.

Selective transformations of secologanin: epoxidation

The oxidation of tetraacetylsecologanin dimethyl acetal (7) by m-chloroperbenzoic acid has been studied and the results have been compared with those obtained when tetraacetylsweroside was oxidized by the same reagent. Complete site selectivity for the vinyl side chain and a relatively low stereoselectivity leading to the formation of a small excess (7:2) of the epoxide with the 3-R configuration was observed with the sweroside derivative. These results parallel those in the osmium tetraoxide oxidation, and the configurations of the glycols produced have been correlated chemically with those of the epoxides. In contrast, there is little site selectivity in the oxidation of the secologanin derivative; in fact, it is the β-alkoxyacrylate site that appears to be oxidized faster to produce an epoxide (9) that then undergoes a second epoxidation at the vinyl side chain. Stereoselectivity is complete in the first epoxidation and is high in the epoxidation of the vinyl side chain, leading to the isomer with the 3-R configuration as the major product. The site selectivity appears to parallel that observed in dihydroxylation of the secologanin derivative, but the stereoselectivity of oxidations at the vinyl side chain is opposite in the two series; the configurations of the glycols and epoxides have been correlated chemically. A rational explanation can be advanced for the observed stereoselectivity in every case, but no convincing argument to explain the observed differences in site selectivity has been found.

Synthesis of 4- C-(1-hydroxyethyl) derivatives from benzyl 2,3-di- O-benzyl- and -2,3- O-methylene-β- l- threo-pentopyranosid-4-ulose, and the corresponding α- d- xylo-hexopyranosid-4-uloses

The title compounds were synthesized by the epoxidation of the corresponding 4- C-vinyl derivatives followed by reduction of the epoxy ring (Route A), and by osmium tetraoxide oxidation of the corresponding 4- C-ethylidene derivatives (Route C). Stereoselectivities in the oxidations are discussed on the basis of the chiralities of 1-hydroxyethyl groups as determined by comparison of the products prepared through Routes A and C.