Baeyer-Vilhger oxidation

The product (6 hexanohde) is a cyclic ester or lactone (Section 19 15) Like the Baeyer-Vilhger oxidation an oxygen atom is inserted between the carbonyl group and a carbon attached to it But peroxy acids are not involved m any way the oxidation of cyclohexanone is catalyzed by an enzyme called cyclohexanone monooxygenase with the aid of certain coenzymes... 

Section 17 16 The oxidation of ketones with peroxy acids is called the Baeyer-Vilhger oxidation and is a useful method for preparing esters... 

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

Baeyer-Villiger oxidation (Section 17 16) Oxidation of an aldehyde or more commonly a ketone with a peroxy acid The product of Baeyer-Vilhger oxidation of a ketone is an ester... 

Tomioka and coworkers reported ketones 15 and 16 as asymmetric epoxidation catalysts (Fig. 5) [42,43]. Ketone 15 was found to be prone to Baeyer-Vilhger oxidation to the lactone, thus giving low yield for the epoxidation (Table 1, entry 14). Epoxidation results were much improved with tricychc ketone 16 (Table 1, entries 15, 24). 

A high catalyst loading (typically 20-30 mol%) is usually required for the epoxidation with ketone 26 because Baeyer-Vilhger oxidation presumably decomposes the catalyst during the epoxidation. The fused ketal moiety in ketone 26 was replaced by a more electron-withdrawing oxazohdinone (32) and acetates (33) with the anticipation that these replacements would decrease the amount of decomposition via Baeyer-Villiger oxidation (Fig. 8) [71, 72]. Only 5 mol% (1 mol% in some cases) of ketone 32 was needed to get comparable reactivity and enantioselectivity with 20-30 mol% of ketone 26 [71]. Since dioxiranes are electrophilic reagents, they show low reactivity toward electron-deficient olefins, such as a, 3-unsaturated esters. Ketone 33, readily available from ketone 26, was found to be an effective catalyst towards the epoxidation of a, 3-unsaturated esters [72]. 

SCHEME 164. Baeyer-Vilhger oxidation using Sn-/i-zeohte/H202... 

Bacteria, ozone disinfection, 616 Bactericides, hydrogen peroxide, 623 Baeyer-Vilhger oxidation, 538-56, 551-66 ketones, 784-7 tin(lV) chloride, 786-7 peroxyester determination, 700-1 Base-catalyzed reactions... 

Bis(trifluoromethyl) peroxycarbonate, 705 Bis(trifluoromethyl) peroxydicarbonate, 705 Bis(trifluoromethyl) trioxide IR spectrum, 740 O NMR spectroscopy, 182 Bis(trifluoromethyl) tiioxydicarbonate, 740 Bis(trimethylsilyl) monoperoxysulfate Baeyer-Vilhger oxidation, 785 catalytic epoxidation, 791-2 Bis(trimethylsilyl) peroxide (BTSP) alcohol oxidation, 787-90 alkyne reactions, 800 aromatic compounds, 794-5 Baeyer-Vilhger ketone oxidation, 784-7 demethylation, 798... 

The half-hfe of the immobihzed CHMO was 2.5 days, which doubled the stability of the free enzyme. CHMO was also immobihzed with a polyethylenimine-porous agarose polymeric composite and subjecting to a dose of y-radiation [113]. After optimization 87% of the activity wais retained and this catalyst was reused for 16 cycles in the Baeyer-VilHger oxidation of a cyclohexanone derivative. 

The addition of peroxyacetic acid to the heteronuclear C=0 double bond of cyclohexanone i.e. the first step of the Baeyer-VilHger oxidation reaction) also exhibits a small solvent dependence [517],... 

Kwart and co-workers have recently proposed a novel 1,3-dipolar mechanism for the Baeyer-Vilhger oxidation with peroxy-acids [J4a]. The peroxy-acid, in its cyclic hydrogen-bonded form (17) is envisaged as adding onto the carbonyl... 

The invention of the triflate (trifluoromethylsulfonyl) group—a superior leaving group—has led to its use in palladium chemistry [42]. Conway and Gribble described the synthesis of 3-indolyl triflate 34 [12] and 2-indolyl triflate 35 from oxindole [43]. Merour synthesized the /V-phenylsulfonyl derivative 36 by employing a Baeyer-Vilhger oxidation of the appropriate indolecarboxaldehyde [44]. 

Interesting development over the last decade of the Baeyer-Vilhger oxidation, originally discovered in the late 19fh century, has opened up opportunities to con-... 

Apart from the asymmetric metal catalysis, enantioselective Baeyer-Villiger oxidations mediated by enzymes have been known for some time [32,33,34]. Both whole-cell cultures and isolated enzymes, usually flavin-dependent monooxygenases, can be used to oxidize ketones enantioselectively. For future improvements in the asymmetric Baeyer-VilHger oxidation the use of chiral Lewis acids in combination with an appropriate oxidant seems worthy of intensive investigation. 

Stereospedfic reachons, 284—286 Baeyer-Vilhger oxidation, 683—684 bimolecular (E2) elimination, 194—196 bimolecular nucleophilic substituhon (Sn2), 307-309, 328, 331 table Diels-Alder reachon, 385, 392—393 epoxidation of alkenes, 238—240, 250, 285, 630... 

The choice of ketone is governed by its ability to form a dioxirane quickly (an electron withdrawing group in the a-position is helpful) and not to be prone to either racemisation or Baeyer-Vilhger oxidation. The intermediate dioxirane must also be willing to donate an oxygen to the alkene substrate. 

Phenols can also be prepared by combining Baeyer-Vilhger oxidation and ester hydrolysis. Oxidation of p-methoxyacetophenone with trifluoroperoxyacetic acid gives 4-methoxy-phenyl acetate as the major product and methyl 4-methoxybenzoate as the minor one. 

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

Waldmann and Kumar reported about an enantioselective [3+2]-cycloaddition of zwitterions generated from allene 91 and chiral phosphine catalyst 92 with cyclopentenones 90 to produce pentalenones 93. Regioselective Baeyer-Vilhger oxidation with bis(monoperoxyphthalate) hexahydrate... 

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