Oxone reaction with amines

An indirect method for generating an amino alcohol (124) is to open an epoxide with azide to give the azido-alcohol 123, and subsequent reduction (19-50) gives the amine group.Sodium azide and Oxone react with epoxides to give an azi-do-alcohol. Under Mitsunobu conditions (10-17), epoxides are converted to 1,2-diazides with The reaction of trimethylsilyl azide and an epoxide was... 

Aliphatic and aromatic primary amines are rapidly and efficiently oxidized to nitro compounds by dimethyldioxirane.111 Dimethyldioxirane is prepared by reaction of OXONE (DuPont trademark)-2KHS05-KHS04-K2S04 with buffered aqueous acetone.112... 

In a typical reaction, w-butylamine (0.052 g, 0.7 mmol) in 5 ml of acetone is treated with 95 ml of dimethyldioxirane in acetone solution (0.05 M). The solution is kept at room temperature for 30 min with the exclusion of light (Eq. 2.53). Aromatic amines are converted into nitro compounds by oxidation using OXONE itself.113... 

Primary, secondary and tertiary aliphatic amines are efficiently converted to nitro compounds in 80-90 % yield with dimethyldioxirane, a reagent prepared from the reaction of oxone (2KHSO5-KHSO4-K2SO4) with buffered acetone. Dimethyldioxirane (DMDO) has been used for the synthesis of 1,3,5,7-tetranitroadamantane (71) from the corresponding tetraamine as the tetrahydrochloride salt (70) and is an improvement over the initial synthesis using permanganate anion (Table 1.7). ° Oxone is able to directly convert some aromatic amines into nitro compounds. 

Aliphatic primary amines are known to be oxidized by dimethyl dioxiranes to various products such as oximes, nitroso dimers, nitroalkanes, nitrones and oxazrridines under various conditions depending upon the oxidation reaction . In contrast, when secondary amines lacking a-hydrogens are allowed to react with Oxone and PTC in buffered acetone solution at 0 °C, nitroxides are obtained in good yields in a few minutes (equation 61) . 

Today, many stable radicals are known, as shown in Figures 1.11 and 1.12. However, most of them are nitroxyl radicals like NO or N02. Standard generation methods of nitroxyl radicals are as follows. One is the oxidation of amines or hydroxyamines by Pb02, or by less toxic oxidants such as oxone, Cu(OAc)2, mCPBA (eqs. 1.13 and 1.14). Another one is the reaction of nitro compounds with Grignard reagents (eq. 1.15) [9-14]. 

Dioxiranes, prepared from acetone and other aliphatic ketones by treatment with Oxone, can accomplish oxidations that are usually not achieved by Oxone itself [210, 211], Dioxiranes can be isolated by vacuum codistillation with the respective ketones [210], or else, they may be formed in situ and applied in the same reaction vessel [210, 211]. Examples of the applications of dioxiranes are epoxidations 210] and the oxidation of primary amines to nitro compounds [211], of tertiary amines to amine oxides [210], and of sulfides to sulfoxides [210] (equation 12). 

For epoxidation to proceed, the presence of base is essential under the aqueous conditions when using Oxone as oxidant. We were pleased to discover that, in contrast, the addition of 1 equiv of any of a range of bases (KF, TBAF, CsF, pyridine, 2,6-lutidine, DBN, DBU, DABCO, LiH, NaH) to the test reaction in dichloromethane at 0 °C, with TPPP as oxidant, did not improve the reaction indeed, the amine bases suppressed epoxidation altogether. 

A Wittig reaction of the THF-swollen polystyrene resin (48) with the P-ketomethylene ylide (49) has been used to functionalise the resin for further transformations. " The aza-Wittig reaction of N-Boc-triphenyliminophosphorane (50) with 4-cyanobenzaldehyde followed by oxone oxidation provides the stable oxaziridine (51) (Scheme 4) which acts as an electrophilic aminating agent towards amines and enolates. ... 

Nitrogen Compounds. The aqueous Oxone-acetone combination has been developed for the transformation of certain anilines to the corresponding nitrobenzene derivatives, as exemplified in eq 15. This process involves sequential oxidation steps proceeding by way of an intermediate nitroso compound. In the case of primary aliphatic amines, other reactions of the nitrosoalkane species compete with the second oxidation step (for example, dimerization and tautomerization to the isomeric oxime), thereby limiting the synthetic generality of these oxidations. An overwhelming excess of aqueous Oxone has been used to convert cyclohexylamine to nitrocyclohexane (eq 16)P... 

Because of Oxone s acidic nature, (V-nitrosation of secondary amines is possible with the use of sodium nitrite in the presence of wet Si02 (eq 55). Nitrophenols can be obtained via nitrosation-oxidation of phenols under similar conditions (eq 56). Although acidic, the use of Oxone for these reactions eliminates the need for strong acids to generate NO+ unlike traditional methods. Nitrosoarenes can also be prepared by oxidation of anilines with Oxone (eq 57). ... 

Oxone adsorbed on silica gel or alumina is a very effective oxidant for the selective oxidation of primary and secondary amines to hydroxylamines without overoxidation. These reactions can even be accomplished under solvent-free conditions and with very short reaction times with heating or microwave irradiation (eq 53). Pyridine and trialkylamines were also readily oxidized to their A-oxides. It is suggested that the hydroxylamines are protected from overoxidation because of their strong adsorption to the silica gel or alumina surface. 

In organic chemistry, oxidation and reduction processes are different from ordinary redox reactions because in many cases they do not involve direct electron transfer but may involve a decrease in electron density around a molecule or loss/gain of hydrogen. Oxidation reactions are useful to convert alcohols into carbonyl compounds, nitriles into acids, and amines into imines. SSA along with a suitable reagent such as oxone or sodium nitrite serves as a powerful oxidant. This part of the chapter encompasses the oxidation reactions catalyzed by SSA. 

Only a limited number of examples of the biocatalytic oxidation of tertiary amines have been reported. Colonna et td. used bovine serrmi albumin (BSA) as a biocatalyst for the asymmetric oxidation of tertiary amines to N-oxides [127]. Oxone, NaI04, H2O2, and MCPBA were tested as oxidants, and the best results were obtained with NaI04 and H2O2 (Eq. (8.30)). Thus, BSA-catalyzed N-oxidation of 36 with these oxidants afforded N-oxide 37 in high yield in 64—67% ee. The reaction is formally a dynamic kinetic resolution, since the enantiomers of the starting material are in rapid equilibrium. 

In 2000, Aggarwal reported the use of simple amines as epoxidation catalysts using Oxone as the stoichiometric oxidant (Scheme 1.48) [96], Yang and co-workers have also reported the effect of substituents on amine catalysed oxidation. It was found that fluorine atoms give the highest catalytic efficiency with 100% conversion, 87% yield and ees of up to 50% (Scheme 1.49). These results were then improved by repeating the reactions at lower temperatures of 0°C to -20°C to afford up to 61% ee [97]. 

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