Allyl oxidation

The slow oxidation of primary alcohols, particularly MeOH, is utilized for the oxidation of allylic or secondary alcohols with allyl methyl carbonate without forming carbonates of the alcohols to be oxidized. Allyl methyl carbonate (564) forms 7r-allylpalladium methoxide, then exchange of the methoxide with a secondary or allylic alcohol 563 present in the reaction medium takes place to form the 7r-allylpalladium alkoxide 565, which undergoes elimination of j3-hydrogen to give the ketone or aldehyde 566. The lactol 567 was oxidized selectively with diallyl carbonate to the lactone 568 without attacking the secondary alcohol in the synthesis of echinosporin[360]. 

These include copolymers of propylene sulphide with 3-10% of allyl glycidyl thioether and which may be considered as a thio-analogue of the propylene oxide-allyl glycidyl ether rubber briefly mentioned in Section 19.5 ... 

Nickel peroxide is a solid, insoluble oxidant prepared by reaction of nickel (II) salts with hypochlorite or ozone in aqueous alkaline solution. This reagent when used in nonpolar medium is similar to, but more reactive than, activated manganese dioxide in selectively oxidizing allylic or acetylenic alcohols. It also reacts rapidly with amines, phenols, hydrazones and sulfides so that selective oxidation of allylic alcohols in the presence of these functionalities may not be possible. In basic media the oxidizing power of nickel peroxide is increased and saturated primary alcohols can be oxidized directly to carboxylic acids. In the presence of ammonia at —20°, primary allylic alcohols give amides while at elevated temperatures nitriles are formed. At elevated temperatures efficient cleavage of a-glycols, a-ketols... 

Oxidation, allylic, 56,25 of alcohols, 55, 84 58,122 Oxime ( -allyl ethers, 58,10 S y-(2-Oxobut-3-yl)butanethioate, 55, 129 4-Oxocarboxylic acid esters, 58, 81 S-substituted, 58, 82... 

Hydroxy(tosyloxy)iodobenzene 2014 reacts with phenyltrimethylsilane 81 in boiling acetonitrile to give diphenyliodonium tosylate 2015 and trimethylsilanol 4 or HMDSO 7 [184, 185]. Likewise, treatment of 2,5-bis(trimethylsilyl)furan 2016 with 2014 in boiling acetonitrile/methanol affords 78% iodonium tosylate 2017 and trimethylsilanol 4 [185]. In the presence of Bp3-OEt2 iodosobenzene oxidizes allyl-trimethylsilanes such as 2018 to unsaturated aldehydes such as 2019 in 63% yield, with formation of iodobenzene and trimethylsilanol 4 [186]. Analogously, vinyltrimethylsilanes such as (Z)-l-trimethylsilyl-2-phenylethylene 2020 afford, via 2021, acetylenes such as phenylacetylene in 61% yield and iodobenzene and trimethylsilanol 4 [187] (Scheme 12.54). 

Tertiary butylhydroperoxide (TBHP) is a popular oxidizing agent used with certain catalysts. Because of its size, TBHP is most effective with catalysts containing large pores however, it can also be used with small-pore catalysts. Using first-row transition metals, Cr and V, impregnated into pillared clays, TBHP converts alcohols to ketones, epoxidizes alkenes, and oxidizes allylic and benzylic positions to ketones.83-87... 

The insight gained from exposure of 36 to oxidants led us to the successful work from the Flowers group utilizing a cerium-mediated oxidative allylation of vinylogous amides [42]. Their investigations used a more soluble source of Ce(IV)... 

Propylene Oxide-Allyl Glycidyl Ether Copolymer (PO, GPO).99... 

Allylic intermediate, 27 185-187 ii-Allylic nickel intermediates, 33 15-18, 22 Allylic oxidation, see Oxidation, allylic Allylic species, 30 21 formation, isomerization, 30 18-19 free allyl radicals, 30 149 a-hydrogen abstraction, 30 147 Allyl methacrylate oxidation, 41 305 Allyls... 

In this transformation, manganese(IV) oxide oxidizes allylic or benzylic alcohols to aldehydes followed by nucleophilic attack of the in situ formed triazolinyli-dene carbene (Scheme 41). The authors suggest the formation of an acyl anion equivalent LX is slow in MeOH compared to oxidation to allow for an activated carboxylate LXII. 

The cross-linking rate of EPR by radiation comes close to that of polypropylene. EPDM terpolymers exhibit an enhanced cross-linking rate, and it increases with the diene content. However, not only the cross-linking rate, but also a greater yield of scissions results from the addition of the third monomer. Cross-linking of EPR can be promoted by the addition of a variety of additives, particularly by those that were found effective in polypropylene. Tetravinyl silane, chlorobenzene, nitrous oxide, allyl acrylate, neopentyl chloride, and N-phenyl maleimide were reported to promote the process. 

Cross-linking of EPR can be promoted by the addition of a variety of additives, particularly by those that were found effective in polypropylene. Tetravinyl silane, chlorobenzene, nitrous oxide, allyl acrylate and neopentyl chloride,191192 and biphenyl maleimide177 were reported to promote the process. 

The redox catalyst [(trpy)(bpy)RuO]2 + jj oxidize allylic methylene groups... 

Palladium-catalyzed allylic oxidations, in contrast, are synthetically useful reactions. Palladium compounds are known to give rise to carbonyl compounds or products of vinylic oxidation via nucleophilic attack on a palladium alkene complex followed by p-hydride elimination (Scheme 9.16, path a see also Section 9.2.4). Allylic oxidation, however, can be expected if C—H bond cleavage precedes nucleophilic attack 694 A poorly coordinating weak base, for instance, may remove a proton, allowing the formation of a palladium rr-allyl complex intermediate (89, path by694-696 Under such conditions, oxidative allylic substitution can compete... 

A -10200 C6HioO CeHioS Mesityl Oxide Allyl sulfide 130.5 139.35 Nonazeotrope 246... 

PDC is able to oxidize allylic positions, resulting in the transformation of alkenes into enones. This reaction normally demands heating and is best performed in solvents other than CH2CI2.140 Very often, r-butyl hydroperoxide is added.141 When a standard procedure for the oxidation of alcohols with PDC is employed, normally no interference with alkenes occurs. 

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