Cis-Oxyamination

By treating the azasulfenylation products with trimethyloxonium tetrafluoroborate, sulfonium salts 5 were obtained, which in acetonitrile at 80 °C underwent decomposition to give the corresponding 4,5-dihydro-l,3-oxazole 6 in good yield. Successive hydrolysis afforded the amino alcohol 7, so that the overall sequence consists of a cis oxyamination of a double bond. 

Nitrogen-transfer reactions of osmium imido species lead to cis diamines or amino alcohols. Reaction of 0s02(N-/-C4H9)2 [63174-13-0] with olefins produces vicinal diamines after reductive cleavage. Catalytic oxyamination of olefins using chloramine-T or AJ-chlor-AJ-argenocarbamates yields vicinal hydroxy toluenesulfonamides (112) or carbamates (113), respectively, which maybe deprotected to vicinal amino alcohols. 

The same researchers found that imino derivatives of Os04 react with alkenes to produce cis-jS-amino alcohols (equation 124).346,347 This oxyamination reaction can be made catalytic in the presence of chloramine salts, e.g. ArS02NClNa or ROCONClAg.348,349... 

OSMIUM-CATALYZED VICINAL OXYAMINATION OF OLEFINS BY CHLORAMINE-T cis-2-(p-TOLUENESULFONAMIDO)CYCLOHEXANOL AND 2-METHYL-3-(p-TOLUENESULFONAMIDO)-2-PENTANOL... 

Recent work has shown that the carbamate reaction shows no legioselectivity in the rather demanding case of 1,2,3,6-tetrahydropyiidines 1,2-dihydropyiidines react at the 5,6 double bond, but with no selectivity in the N,0 orientation. The regioselectivities of the Sharpless oxyaminations have been rationalize, and the react on has recently been studied from the point of view of the inoiganic chemist These procedures and ther cis hydroxyaminations below produce stereochemistry complementaiy to that provided by ring Of ming of the epoxidized alkene. ... 

The explanation for the dual stereocontrol in the oxyamination reaction is as follows in the absence of chloride ligand, cis migration of coordinated acetate is observed from the intermediate 7t-allyl complex, whereas added chloride blocks the coordination of acetate to palladium and forces the external attack of acetate to take place. The relative stereochemistry, referring to the addition across the diene system, was established by H-NMR spectroscopy. 

The oxyamination of C-2 C-3 and C-3-C-4 unsaturated sugars gave mixtures of regioisomeric hydroxy amides, i.e., 12, 13 and 14, 158s-91. The cis dihydroxylation was often a competitive reaction, especially for C-2-C-3 unsaturated sugars, e.g., formation of 1888-91. The products were generally separated by column chromatography. 

Nitroso compounds generally react as dienophiles with 1,3-dienes to give 3.6-dihydro-2//-1,2-ox-azines 1 through a [4 -I- 2] addition proceeding in a stereoselective cis mode. The overall process, carried out on cyclic or 1,4-disubstituted dienes, consists of a diastereoselective 1,4-oxyamination of the diene moiety1 - 3. 

Palladium-catalyzed oxidation of dienamides 88 in acetone in the presence of acetic acid gives oxyamination products in stereoselective reactions (Scheme 8-33) [113]. Depending on the reaction conditions, it is possible to obtain trans- or cis-1,4-oxyamination by choice. As with the other palladium(II)-catalyzed 1,4-additions, CI (from LiCl) is used as a... 

Oxyamination of olefins. This reagent reacts with a variety of olefins to give, after reductive cleavage of intermediate osmate esters, cis-vicinal amino alcohols in fair to high yield. The reaction is regiospecific in that the new C—N bond is formed at the least substituted carbon atom of the olefin. The reagent reacts more rapidly with monosubstituted olefins than with di- and trisubstituted olefins. Diols are obtained as the main products from hindered olefins. Methylene chloride or THF can be used as solvents, but pyridine is the solvent of choice. 

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