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Ketones, aryl oxidative rearrangement

Acyl substituents at the 3- and/or 4-positions result in decreased hydrolytic stability compared with the alkyl and aryl derivatives described above. Despite this constraint most of the usual reactions of the carbonyl group are possible. Aldehydes <9ILA1211> and ketones are oxidized to the carboxylic acid, borohydride reduction affords the expected alcohols, and epoxides are formed on reaction with diazomethane. Oximes and arylhydrazones are formed with hydroxylamine and arylhydrazines, and the products may subsequently undergo monocyclic rearrangement involving the oxadiazole to give the corresponding isomeric furazans and 1,2,3-triazoles (Section 4.05.5.1.4). [Pg.247]

Methyla-arylacetates. These esters have been obtained by oxidative rearrangement of alkyl aryl ketones with thallium(III) nitrate in acidic methanol or trimethyl orthoformate (4,496 5, 656 7, 362). A new method, which avoids the toxic TTN, is based on the Woodward version of the Prevost reaction. Thus, treatment of the ketone with iodine (or bromine) and silver nitrate (2 equiv.) in refluxing methanol containing trimethyl orthoformate results in methyl a-arylacetates in 90% yield from simple substrates. Yields are lowered by electron-withdrawing substituents on the aromatic group and by a-branching in the alkyl group.2... [Pg.139]

Oxidative rearrangement of aryl methyl ketonesThese ketones have been converted into methyl a-methoxyarylacetates on reaction with T1(N03)2 in trimethyl orthoformate (7, 362). This oxidative rearrangement can also be effected with C6H5I(OAc)2 (2 equiv.) in trimethyl orthoformate in equally good yield. [Pg.275]

Carbon-Oxygen Bond Formation. CAN is an efficient reagent for the conversion of epoxides into /3-nitrato alcohols. 1,2-cA-Diols can be prepared from alkenes by reaction with CAN/I2 followed by hydrolysis with KOH. Of particular interest is the high-yield synthesis of various a-hydroxy ketones and a-amino ketones from oxiranes and aziridines, respectively. The reactions are operated under mild conditions with the use of NBS and a catalytic amount of CAN as the reagents (eq 25). In another case, N-(silylmethyl)amides can be converted to A-(methoxymethyl)amides by CAN in methanol (eq 26). This chemistry has found application in the removal of electroauxiliaries from peptide substrates. Other CAN-mediated C-0 bondforming reactions include the oxidative rearrangement of aryl cyclobutanes and oxetanes, the conversion of allylic and tertiary benzylic alcohols into their corresponding ethers, and the alkoxylation of cephem sulfoxides at the position a to the ester moiety. [Pg.84]

Methyl esters of a-arylalkanoic acids 907 can be prepared by oxidative rearrangement of ketones 906 via a 1,2-aryl shift using iodic acid in methanol in the presence of trimethyl orthoformate and sulfuric acid (Scheme 3.364) [1304]. [Pg.303]

The chemistry of lead tetrakistrifluoroacetate and aryl-lead tristrifluoroacetates has continued to merit considerable attention. Norman and his co-workers, in a study of the oxidative rearrangement of styrene and related compounds to aldehydes and ketones, have found that the preferred reagent is(CF3 C02)4Pb-CF3 C02H at 20 C. The yields obtained (see Table 4) for the 1-methylstyrenes increase in the order 4-Me < 4-H < 4-NO2, which runs opposite to that expected on the basis of migratory aptitudes 1-methylstyrene also gave the dimer (33) (39%). High yields... [Pg.144]

A review of oxidative rearrangements induced by iodine(III) and iodine(V) reagents has appeared.Enantioselective rearrangements of alkenes to a-arylated ketones have been promoted using lactic-acid-based iodine(lll) reagents (Scheme 108). ... [Pg.561]

Aryl alkyl ketones 61 undergo oxidative rearrangement to a-arylalkanoic acids 62 [Eq. (20)] [404], which are industrially important intermediates for the synthesis of compounds with anti-inflammatory properties. [Pg.226]

Three types of photoextrusion reactions have been identified in the irradiation of aryl-substituted 1,3,2-dioxathiolane 2-oxides [5 1-1-2 4-2] cycloelimination to produce a carbonyl compound, a carbene and sulfur dioxide extrusion of sulfur dioxide accompanied by a pinacol-like rearrangement to yield an aldehyde or ketone and extrusion of sulfur trioxide to give an alkene <72JOC2589>. Sensitization and quenching experiments indicate that a singlet state is responsible for the cycloelimination reaction, whereas the rearrangement and sulfur trioxide extrusion reactions arise from a triplet state <82JCR(S)175>. [Pg.559]

Bromination of the enol ether product with two equivalents of bromine followed by dehydrobromination afforded the Z-bromoenol ether (Eq. 79) which could be converted to the zinc reagent and cross-coupled with aryl halides [242]. Dehydrobromination in the presence of thiophenol followed by bromination/dehydrobromination affords an enol thioether [243]. Oxidation to the sulfone, followed by exposure to triethylamine in ether, resulted in dehydrobromination to the unstable alkynyl sulfone which could be trapped with dienes in situ. Alternatively, dehydrobromination of the sulfide in the presence of allylic alcohols results in the formation of allyl vinyl ethers which undergo Claisen rearrangements [244]. Further oxidation followed by sulfoxide elimination results in highly unsaturated trifluoromethyl ketonic products (Eq. 80). [Pg.162]

Oxidation of enamines.1 Oxidation of enamines of cyclic ketones in the presence of BFj etherate results in a Favorski type rearrangement to esters of contracted cycloalkanoic acids. A related reaction also occurs with enamines of aryl methyl ketones. [Pg.228]


See other pages where Ketones, aryl oxidative rearrangement is mentioned: [Pg.829]    [Pg.829]    [Pg.829]    [Pg.864]    [Pg.827]    [Pg.845]    [Pg.827]    [Pg.845]    [Pg.28]    [Pg.52]    [Pg.799]    [Pg.864]    [Pg.210]    [Pg.100]    [Pg.827]    [Pg.845]    [Pg.169]    [Pg.302]    [Pg.580]    [Pg.82]    [Pg.1411]    [Pg.1567]    [Pg.255]    [Pg.354]    [Pg.219]    [Pg.554]    [Pg.478]    [Pg.580]    [Pg.478]    [Pg.580]   
See also in sourсe #XX -- [ Pg.829 ]

See also in sourсe #XX -- [ Pg.829 ]

See also in sourсe #XX -- [ Pg.7 ]

See also in sourсe #XX -- [ Pg.7 ]

See also in sourсe #XX -- [ Pg.829 ]




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Aryl ketones

Aryl rearrangements

Arylic oxidation

Aryls oxides

Ketones aryl, oxidation

Ketones aryl, rearrangement

Ketones arylation

Ketones oxidant

Ketones oxidation

Ketones rearrangement

Oxidation oxidative rearrangement

Oxidation rearrangements

Oxidative arylation

Oxidative ketones

Oxidative ketonization

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