Oxidative of cyclic ketones

The November 2001 issue of the Journal of Chemical Education ipp 1533-1534) describes an introductory biochemistry laboratory ex periment involving cycio hexanone monooxygenase oxidation of cyclic ketones... 

Compounds known as lactones, which are cyclic esters, are formed on Baeyer—Villiger oxidation of cyclic ketones. Suggest a mechanism for the Baeyer—Villiger oxidation shown. 

Transition metal catalysis in Baeyer-Villiger oxidation of cyclic ketones with formation of lactones 98AG(E)1198. 

For the oxidation of ketones, Baeyer-Villiger oxidation of cyclic ketones with monopersuccinic acid in water gives lactones in good results (Eq. 8.22).47 Peroxy species generated from borax in 30% hydrogen peroxide is effective for the Baeyer-Villiger oxidation of... 

Microwave synthesized mesoporous Tin MFI as efficient catalyst for Baeyer-Villiger Oxidation of cyclic ketones... 

Correlation of structure and reactivity in the oxidation of substituted aromatic anils by pyridinium fluorochromate (PFC) has been attempted using Grunwald-Winstein and Hammett equations. The stoichiometry between the substrate and oxidant is 1 2 in the oxidation of cyclic ketones by PFC to 1,2-diketones. PFC oxidation of secondary alcohols has been investigated. ... 

Oxidation of cyclic ketones by H2O2 in the presence of an acid zeolite was used for the preparation of lactones and u-hydroxycarboxylic acids [124]. Thus, for c-pentanone oxidation in the presence of H-ZSM-5, -valerolactone is obtained with 62.3% selectivity at 40% conversion, whereas 5-hydroxy-pentoic acid is obtained with 34% yield in the presence of Zeolon M. 

The first report of transition-metal peroxides active in the BV oxidation of cyclic ketones was due to Mares and coworkers in 1978 . These authors found that Mo-peroxo complexes, containing picolinato 101 and especially dipicolinato ligands 105, are able to mediate the transformation of some cyclopentanones and cyclohexanones to the corresponding lactones by concentrated H2O2 (equation 70) with yields in the range... 

The Baeyer-Villiger oxidation of cyclic ketones was also achieved by the MTO/H2O2 system in the ionic liquid [BMIM][BF4 [78] (Scheme23). Kinetic investigations have additionally been performed in order to follow the formation of the catalytically active peroxorhenium intermediates in the RTILs [81,82]. 

Other Peroxyacids. Benzeneperoxyseleninic acid has been prepared in situ from benzeneseleninic acid and hydrogen peroxide and is used to epoxidize terpenic olefins and Baeyer-Villiger oxidation of cyclic ketones. 

Tin-containing silicalite-2, Sn-Sil-2, has been synthesized [107]. From an 119Sn NMR study, however, it has been suggested that Sn4+ ions are mostly in octahedral coordination. Sn-beta catalyzes the Baeyer-Villiger oxidation of cyclic ketones to lactones without using peracids but using H202 [108]. 

Mn(II)-catalyzed oxidation of cyclic ketones with lead tetraacetate is zero order in the oxidant. The order of reactivity is cyclohexanone > cyclooctanone > cycloheptanone cyclopentanone. The reactivity has been analysed in terms of the conformation.80... 

The kinetics of the oxidation of cyclic ketones by Caro s acid (peroxomonosulfuric acid, H2SO5) are first order in both, and the pH-rate profile has been analysed in terms of contributions from HSO5- and SOs2-.322 Similar results are found for aromatic aldehydes.323... 

Sn[N(S02C8F17)2]4 catalyst in a similar system also gives an excellent yield and selectivity for Baeyer-Villiger oxidation of cyclic ketones using 35% aqueous hydrogen peroxide (Equation (104)).270... 

Whilst the majority of the discussion thus far has been concerned with metallo-substituted redox molecular sieves, it is important to note that proto-nated zeolite forms can also be employed for selective oxidation with aqueous hydrogen peroxide. An excellent example of this is the study conducted by the Mobil Oil Corporation.52 Their work has shown that a number of protonated zeolites such as H-ZSM-5 or zeolite-/ can be used with hydrogen peroxide to catalyse the oxidation of cyclic ketones to lactones or the co-hydroxycarboxylic acids (Figure 4.12). 

Figure 4.12 Oxidation of cyclic ketones with aqueous hydrogen peroxide in the presence of protonated zeolites.

With < 1 mol% MTO cyclobutanones are fully converted within one hour. Another approach consists of the use of a fluorous Sn-catalyst under biphasic conditions [245]. A perfluorinated tin(IV) compound, Sn[NS02C8F17]4, was recently shown to be a highly effective catalyst for BV oxidations of cyclic ketones with 35% hydrogen peroxide in a fluorous biphasic system (Fig. 4.83). The catalyst, which resides in the fluorous phase, could be easily recycled without loss of activity. 

A final oxidation type that has been observed is the catalysis of Baeyer-Villiger-type oxidations of cyclic ketones to lactones.53 Understandably, the strained cyclobutanone is the best substrate, giving 80% conversion after 24 h at 25°C (tert-butanol solvent). Larger ring ketones proceed more slowly, although selectivity remains high. Elevated temperatures increase the rate without sacrificing selectivity cyclopentanone is converted to the lactone in 72% yield after 1 h at 70°C in THF. Complex 4 was presumed to be the active species. 

Since the isolation of the oxygenating enzyme and recycling of the cofactor is still difficult for large-scale preparations, the use of whole microorganisms would seem to be advantageous. Whole cells of Acinetobacter are well suited for enantioselective Baeyer-Villiger oxidation of cyclic ketones when a lactone hydrolase inhibitor is used or a hydrolase deficient mutant is... 

Miyake, Y., Nishibayashi, Y., Uemura, S. Asymmetric Baeyer-Villiger oxidation of cyclic ketones using chiral organoselenium catalysts. Bull. Chem. Soc. Jpn. 2002, 75, 2233-2237. 

The anhydrous reagent gives improved results in the Baeyer-Villiger oxidation of cyclic ketones to lactones. Thus cyclopentanone afforded 8-valerolactone in... 

High yields are obtained also in the oxidation of cyclic ketones to the ring-expanded lactones. ... 

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