Reaction with Oxone

Recently, Crousse and coworkers reported that new fluoro ketones serve as efficient catalysts for the epoxidation reactions with Oxone in hexafluoropropan-2-ol (HFIP) (equation 46). ... 

Fig. 1.15 Oxidation reactions with Oxone as the oxidant (see for example B. R. Travis,...

Aromatic methyl ketones can be halogenated at the a-position with Oxone and sodium halide, however, corr5>eting halogenation of the aromatic ring is significant. Q, a-Dichloroketones can be synthesized from alkynes by reaction with Oxone in HCl/DMF (eq 83). Oxone consistently gave better results than MCPBA for this transformation. 

Fig. 1.15 Oxidation reactions with Oxone as the oxidant (see for example B. R. Travis, M. Sivakumar, G. O. Hollist, B. Borhan, Org. Lett. 2003, 5, 1031-1034).

Works on the oxidation of uric acid has unequivocally established the triazine structure > ° (9) of oxonic acid. This is further confirmed by the straightforward synthesis described by Piskala and Gut. ° The reaction of biuret (11) with potassium ethyloxalate yielded a potassium salt (24), that with ethyl oxamate, the amide of oxonic acid (25). Both these compounds were converted to 5-azauracil. An analogous reaction with diethyloxalate which should produce an ester of oxonic acid resulted in a mixture of urethane and parabanic acid, however. 

Tlie reaction of 5,6-dithiabicyclo[2.1.1]hexaiie 11a with OXONE led to the corresponding dithiirane 12a, which was, however, stable only in solution (Amax at 442 nm in CH2CI2). Treatment of the reaction mixture containing 12a with MCPBA gave the dithiirane 1-oxide 13a (8%) (95TL1867). Tire introduction of electron-withdrawing substituents on the benzene rings provided the dithiirane oxide 13b in a better yield (21%). 

Tire reaction of 1,3-dithietanes 14 with OXONE produced dithiirane 1-oxides 15 directly (95TL1867). Dithiirane 1-oxides 15 would be formed through the initially formed 1,3-dithietane oxides. 

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... 

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. 

Oxidation of 3,6-diamino-1,2,4,5-tetrazine (198) with oxone in the presence of hydrogen peroxide yields 3,6-diamino-l,2,4,5-tetrazine-2,4-dioxide (201) (LAX-112). The same reaction with 90 % hydrogen peroxide in trifluoroacetic acid yields 3-amino-6-nitro-1,2,4,5-tetrazine-2,4-dioxide (202). Treatment of 3,6-diamino-1,2,4,5-tetrazine (198) with 2,2,2-trinitroethanol and 2,2-dinitro-2-fluoroethanol generates the Mannich condensation products (203) and (204) respectively. 

Asymmetric epoxidation of olefins is an effective approach for the synthesis of enan-tiomerically enriched epoxides. A variety of efficient methods have been developed [1, 2], including Sharpless epoxidation of allylic alcohols [3, 4], metal-catalyzed epoxidation of unfunctionalized olefins [5-10], and nucleophilic epoxidation of electron-deficient olefins [11-14], Dioxiranes and oxazirdinium salts have been proven to be effective oxidation reagents [15-21], Chiral dioxiranes [22-28] and oxaziridinium salts [19] generated in situ with Oxone from ketones and iminium salts, respectively, have been extensively investigated in numerous laboratories and have been shown to be useful toward the asymmetric epoxidation of alkenes. In these epoxidation reactions, only a catalytic amount of ketone or iminium salt is required since they are regenerated upon epoxidation of alkenes (Scheme 1). 

Previously, some fluorocyclohexanones were used in a catalytic amount with Oxone for asymmetric epoxidation reaction, but they gave a poor ee . It was found later that chiral ketones derived from fructose work well as asymmetric epoxidation catalysts and show high enantioselectivity in reactions of /rani-disubstituted and trisubsti-tuted olefins ". Cis and terminal olefins show low ee under these reaction conditions. Interestingly, the catalytic efficiency was enhanced dramatically upon raising the pH. Another asymmetric epoxidation was also reported using Oxone with keto bile acids. ... 

Recently, Borhan and coworkers reported the facile oxidation of aliphatic and aromatic aldehydes to acids and esters in DMF or methanol with Oxone (equation 53) . These reactions are considered to be valuable alternatives to traditional metal-mediated oxidations. 

Sato and coworkers reported recently an interesting oxidation reaction of 1,4-dihydro-l,4-diphenyl-2,3-benzodithiin . When compound 38 was treated with m-CPBA in CH2CI2, ring contraction to l,3-diphenylbenzo[c]thiophene 39 was observed. With H2O2 in CH3COOH, the reaction afforded l,3-dihydro-l,3-diphenylbenzo[c]thiophene 40, while with Oxone a highly regioselective oxidized product, i.e. l,4-dihydro-l,4-diphenyl-2,3-benzodithiin 2,2-dioxide 41, was formed (equation 58). 

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) . 

A new method for conversion of oximes to the corresponding em-halonitro derivatives using NaCl or KBr with Oxone and wet basic alumina was reported (equation 64) °. When the reaction was carried out under the same conditions but by using wet neutral alumina, complex mixtures of compounds in which the parent ketone is the most abundant product (>50%), due to the oxidative deprotection of the oxime, was obtained. 

Regeneration of ketones from tosylhydrazones with Oxone in acetone has been reported. Under controlled pH (pH = 6) the reaction gave very high yield (90%) of the product. In this paper we demonstrated that the use of in situ formed dimethyldioxirane under controlled pH conditions gives better results (equation 66). 

When a variety of aldehydes and Af,Af-dimethylhydrazones are treated with Oxone on wet AI2O3 under microwave irradiation in the absence of a solvent, the corresponding nitriles are obtained in good yields. Under these reaction conditions high selectivity... 

Primary, secondary and tertiary thioamides and thionreas are readily converted to their corresponding 0x0 analogs with Oxone in refinxing CH3CN . Thiono esters were converted to esters, while thioketones remained intact nnder these reaction conditions. Hydrazines can be selectively converted to esters and acids in high yields by nsing Oxone in an alcohol and a water, respectively . However, Mane and coworkers showed that hydrazides can be smoothly converted into the corresponding Af,Af -diacylhydrazines in excellent yields with Oxone in water (equation 67) . ... 

Methylisothiazolo[5,4- ]pyridin-3-(2//)-one-l-oxide 103 was quantitatively obtained by treating 104 with chlorine in aqueous acetic acid (Equation 13). The oxidation of 104 with Oxone at 60 °C in aqueous methanol gave 2-methylisothiazolo[5,4- ]pyndin-3-(2//)-one 1,1-dioxide 105 in a single step (Equation 14). No C-halogenation or N-oxidation products were detected under these reaction conditions <1996T8947>. 

In the attempted synthesis of isothiazolo[5,4-3]pyridin-3(2//)-one 1,1-dioxide 172, direct oxidation of isothi-azolo[5,4-/ ]pyridin-3(2//)-one with either Oxone /MeOH, 3-chloroperoxybenzoic acid/CH2Cl2, or KMn04/AcOH did not afford the desired product. However, this compound was synthesized in good yield by treatment of 173 with chlorine in aqueous HCl and subsequent reaction with ammonia in ethanol (Scheme 14) <1996T8947>. 

Chiral ketone-catalyzed asymmetric epoxidation has received intensive interest since the first reported by Curci et al. in 1984. The reaction is performed with oxone (potassium peroxomonosulfate) as the primary oxidant which generates the chiral dioxirane catalytic species in situ, which in turn, transfers the oxygen... 

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