Dimethyldioxirane DMDO

Dimethyldioxirane DMDO discovered by Murray and coworkers, is a superior choice for the epoxidation of most olefins, giving comparable or higher yields than m-CPBA-based epoxidation [21]. Proceeding rapidly under neutral and mild conditions, it is especially well suited for the synthesis of sensitive epoxides of enol esters, enol lactones [22], and enol ethers [23]. The reaction is stereospecific, gen-... 

Epoxidation by Dioxirane Derivatives. Another useful epoxidizing agent is dimethyldioxirane (DMDO),86 which is generated by in situ reaction of acetone and peroxymonosulfate in buffered aqueous solution. Distillation gives about aO.lM solution of DMDO in acetone.87... 

Upon treatment with dimethyldioxirane (DMDO), benzannulated dihydropyrrolizine 84 afforded two dimers 86 and 86, each as a mixture of two diastereomers < 1997JA1159>. The zwitterionic species 85 is postulated as intermediate in these dimerizations (Scheme 10). 

Only a few isolated allene oxides have been synthesized from allenes and characterized. Most often peracids are used but the oxidative and acidic conditions usually result in a complex mixture of products. To overcome this problem, dimethyldioxirane (DMDO) can be used, which rapidly oxidizes allenes to spirodiepoxides. Several synthetically useful methods have been developed via in situ reaction of the intermediate allene oxide or spirodioxide with different nucleophiles. 

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. 

Peroxyacids are the most widely used class of oxidant for aromatic amino to nitro group conversion and include peroxydisulfuric, peroxymonosulfuric, peroxyacetic, peroxytrifluo-roacetic and peroxymaleic acids. The oxidizing potential of the peroxyacid is, as a rule, proportional to the strength of the parent deoxy-acid. Dimethyldioxirane (DMDO) and ozone have also found use for amino to nitro group conversion. 

TABLE 2. Comparison of the calculated barriers (kcal mol ) for the oxidation of alkenes, dimethyl sulfide, trimethylamine and trimethylphosphine with peroxynitrous add, peroxyformic acid and dimethyldioxirane (DMDO)... 

FIGURE 13. B3LYP/6-311- -G(3df,2p)-optimized stractures of dioxirane (DO), dimethyldioxirane (DMDO) and methyl(trifluoromethyl)dioxirane (TFDO). Bold numbers for DO are experimental microwave-stractural data. ... 

TABLE 3. B3LYP/6-31G(d) activation barriers (A , kcal mol ) for the epoxidation of a series of alkenes with peroxyformic acid (PFA) and dimethyldioxirane (DMDO). The barriers in parentheses are at the B3LYP/6-31- -G(d,p) level of theory. Other computational approaches are indicated by footnotes. The barriers have been computed with respect to isolated reactants... 

The barrier in brackets for ethylene is at the QCISD(T)//QCISD/6-31- -G(d,p) level Classical activation barriers compnted at the B3LYP/6-311- -G(3df,2p)//B3LYP/6-31- -G(d,p) level The barrier in brackets for li-2-bntene is at the QClSD(T)//QClSD/6-31G(d) level of theory QC1SD(T)/ 6-31G(d)//B3LYP/6-311-lG(3df,2p) gas-phase intrinsic barrier (AE ) for the epoxidation of -2-bntene with dimethyldioxirane (DMDO) is 14.3 kcalmoL. ... 

Distortionless enhancement by polarization transfer (DEPT), 725-6 Disubstituted alkenes, regioselectivity, 842-4 o-Ditoluidine, glucose determination, 632, 634 o,o -Dityrosine, low-density lipoprotein, 610 DMD see Dimethyldioxirane DMDO see Dimethyldioxirane DNA... 

TABLE 5. Calculated [B3LYP/6-311+G(d,p)] activation parameters (kcal mol-1 and eu) for the epoxidation of cyclohexene and isobutene with dimethyldioxirane (DMDO), peroxybenzoic acid (PBA), m-chloroperoxybenzoic acid (m-CPBA) and peroxyformic acid (PFA). Solvent corrections were performed with the COSMO model. The numbers in bold are experimental values95-136. Numbers in parentheses are at the B3LYP/6-311+G(3df,2p)//B3LYP/6-311+G(d,p) level of theory... 

TABLE 6. Classical reaction barriers (AE, kcal mol ) for ethylene epoxidation with peroxy-formic acid (PFA) and dimethyldioxirane (DMDO) at various levels of theory... 

By H NMR monitoring of the oxidation of benzene oxide-oxepine with dimethyldioxirane (DMDO), a significant by-product, oxepine 4,5-dioxide, was identified <1997CRT1314>. This fact supports the hypothesis that the route from oxepine to muconaldehyde proceeds via oxepine 2,3-oxide with a minor pathway leading to symmetrical oxepine 4,5-oxide. The DMDO oxidations provide model systems for the cytochrome P450-dependent metabolism of benzene and atmospheric photooxidation of benzenoid hydrocarbons. 

Dioxiranes (32) are isomeric with carbonyl oxides (33), one of the peroxidic intermediates involved in the ozonolysis process.9 Dimethyldioxirane (DMDO) (31) epoxidizes the double bond of the protected galactal favoring the Oepoxide 8 with a selectivity of 20 1.10,11 You can use 31 likewise to transform an aldehyde into a carboxylic acid. 

Methylene oxetanes have been used as substrates for the synthesis of l,5-dioxaspiro[3.2]hexanes. Epoxidation of the methylene group was achieved using dimethyldioxirane (DMDO), often in quantitative yield (Equation 25) <1998JOC6098>. 

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