Hydroperoxides nucleophilic substitution

The reverse emulsion stabilized by sodium dodecylsulfate (SDS, R0S03 Na+) retards the autoxidation of dodecane [24] and ethylbenzene [21,26,27]. The basis for this influence lies in the catalytic decomposition of hydroperoxides via the heterolytic mechanism. The decay of hydroperoxides under the action of SDS reverse micelles produces olefins with a yield of 24% (T=413 K, 0.02mol L 1 SDS, dodecane, [ROOH]0 = 0.08 mol L 1) [27], The thermal decay gives olefins in negligible amounts. The decay of hydroperoxides apparently occurs in the ionic layer of a micelle. Probably, it proceeds via the reaction of nucleophilic substitution in the polar layer of a micelle. 

While some phenol is produced by the nucleophilic substitution of chlorine in chlorobenzene by the hydroxyl group (structure 17.17), most is produced by the acidic decomposition of cumene hydroperoxide (structure 17.18) that also gives acetone along with the phenol. Some of the new processes for synthesizing phenol are the dehydrogenation of cyclohexanol, the decarboxylation of benzoic acid, and the hydrogen peroxide hydroxylation of benzene. 

B. Cyclization of Hydroperoxides through Intramolecular Nucleophilic Substitution and Addition... 

Cyclic peroxides can be prepared from hydroperoxides and their synthetic equivalents throngh processes involving intramolecular nucleophilic substitution at a carbon... 

Unsymmetrical dialkyl peroxides can be prepared by several methods. Some of them are summarized in Scheme 31. Primary " , secondary or tertiary"" " alkyl hydroperoxides can serve as substrates and are converted to the dialkyl peroxides by acid- or base-catalyzed nucleophilic substitution with alkylating agents like dialkyl sulfate " , diazomethane " , dialkyl sulfites, alcohols " or alkyl halides (e.g. in the presence of silver trifluoroacetate) "". An overview of the results obtained utilizing the method mentioned above is given in Table 7. 

The introduction of substituents into position 7 of a 2,4-disubstituted pteridine can be effected very cleanly by the use of acyl radicals typically and has been known for many years. Treatment of aldehydes with /-butyl hydroperoxide and iron(ll) generates acyl radicals which add selectively to the 7-position. A recent exploitation of this chemistry has provided a large number of new examples including both aryl and alkyl acyl radicals as reagents <2004PTR129> pA , data have been compiled (Section 10.18.4) and many nucleophilic substitution reactions of the 7-acylated pteridines and functional group modifications have been described (Section 10.18.7.2). 

Id (Scheme 3)13. This was prepared via the corresponding phosphite, which can be synthesized by reaction of the alcohol with chlorodiethyl phosphite and triethylamine. The phosphite then undergoes nucleophilic substitution reaction with anhydrous H2O2 forming the hydroperoxide Id (enantiomeric ratio S/R 65/35) and isomeric hydroperoxide le in a 2 1 mixture in 74% overall yield starting from the alcohol. Purification was possible by normal-phase HPLC. So in this case transformation of the phosphite to the hydroperoxide proceeds with partially retained configuration. 

The reaction between alkyl hydroperoxides and enones has also been carried out using the same catalyst 28c and showing a similar behavior (Scheme 3.31). While the reaction usually leads to the formation of an epoxide as final product, under the optimized conditions and, in particular, by the correct election of the alkyl hydroperoxide nucleophile, the reaction can be directed to the formation of the p-peroxy-substituted ketone product in excellent yields and enantioselectivities. Reduction of these adducts allowed the preparation of the corresponding p-hydroxy ketone, therefore showing that the methodology is suitable for carrying out the formal enantioselective conjugate addition of OH to enones. 

Keywords Alkyl hydroperoxides Amination Ammonia Benzimidazole Benzisoxazole Carbanions Heterocycles Hydroxylation Indole Nitro compounds Nucleophiles Nucleophilic substitution Oxidation Phenazine Potassium permanganate Pyridine Quinoline Sulfones Vicarious... 

Nitrothiophene undergoes nucleophilic hydroxylation by applying potassium terf-butyl hydroperoxide, probably via a vicarious nucleophilic substitution (VNS) process. The only product was a rather unstable 3-hydroxy-2-nitrothiophene potassium salt, which could be converted into the more stable tetrabutylammonium salt (Scheme 105) [165]. 

The last VCD example by Lattanzi et al. describes the use of VCD and DFT calculations to assign the absolute configuration of a recently prepared (15,4/ )-norcamphor-derived furyl hydroperoxide, (+)-8, introduced as a less hindered and more reactive stereoselective oxidant in organic synthesis. During the preparation of 8 through the hydroperoxidation of an alcohol precursor via nucleophilic substitution, it is expected that epimerization will occur at carbon 2 of the bicyclic framework leading to the formation of either exo- or endo-8 (Figure 53.25). Therefore, the... 

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