Oxidation benzylic compound

As far as the reactions with benzyl chlorides are concerned (74), the oxidative addition of benzyl chloride and substituted benzyl chlorides to palladium atoms yields rj -benzylpalladium chloride dimers. The parent compound, bis(l,2,3-7 -benzyl)di-/i,-chloro-palladium(II), quantitatively adds four molecules of PEts by first forcing the rj -benzyl-iy -benzyl transformation, with subsequent breakage of the Pd-Cl bridges to form trans-bistPEtsKbenzyDchloroPddI). The spectral characteristics of the parent molecule are indicative of the allylic type of bonding. Similar i7 -benzyl compounds were formed from 4-methylbenzyl chloride, 2-chloro-l,l,l-trifluoro-2-phenylethane, and 3,4-dimethylbenzyl chloride. 

KMn04 (2.37 g, 15 mmol), KOH (0.28 g), and TBA-HS04 (0.34 g, 1 mmol) in H20 (35 ml) are added to the benzylic compound (10 mmol) in CH2C12 (35 ml) and the mixture is stirred at room temperature until the purple colour disappears (orTLC analysis shows complete oxidation). The mixture is acidified with AcOH (5 ml) and Na2SO, is added until the brown colour disappears. The organic phase is separated, washed well with H20, dried (Na2S04), and evaporated to yield the ketone (e.g. PhCOPh, 80% 2-pyridylCOPh, 75% 9,10-anthraquinone from 9,10-dihydroanthracene, 90%). 

Carbonylat ion of 13 4-nitrophenyloxycarbonyl chloride (J 6) in pyridine] gave a good yield of the trityl ether-carbonate 14 which was de-tritylated by hydrogenolysis (2 4) to afford the 7,8-diol-4,5-carbonate 15 in practically quantitative yield. Compound 15.. by way of its 7,8-0 -dibutylstannylidene derivative (25> 26) was regioselectively 8-0-benzylated (dibutyltin oxide, benzene, reflux then benzyl bromide, dimethyl formamide, 95 ), in fair yield (J ). Finally, the aglycon U3 was obtained in high yield by sequential 7-Q-tert.-butyldimethylsilylation (27) (compound 17) and Zemplen saponification. 

Oxidation of benzylic groups K2S208 in the presence of catalytic amounts of ( uS04 is effective for oxidation of benzylic compounds to carbonyl compounds, lixamples ... 

Oxidation with ozone, under physiological conditions, follows the rate order uric acid ascorbic acid > glutathione. The amounts of ozone absorbed and antioxidant consumed have been simulated with a mathematical model and reaction rate constants of the oxidations have been evaluated.194 Various facets of transition metal-catalysed oxidation of benzylic compounds with ozone have been reported. The correlation of the effect of substituents with Hammett constants and steric factors has been discussed. The reaction seemed to proceed via a radical mechanism.195... 

MRH values calculated for 13 combinations with oxidants are given. See other BENZYL COMPOUNDS, PEROXIDISABLE COMPOUNDS... 

Bats, 54 Batteries, 54 Benzene isomers, 55 Benzyl compounds, 55 Bis(arenediazo) oxides, 56 Bis(arenediazo) sulfides, 56 Bis(difluoroamino)alkyl nitrates, 56 Bis(fluorooxy)perhaloafkanes, 57 Bis(sulfur)diimides, 57 Bitumen, 57 Bleaching powder, 57 Bleve, 58... 

The oxidation of the S atom of 4-substituted 2,4,6-triphenyl-47/-thiopyrans with either NaKT/MeOH/AcMe or H2O2/ACOH affords mixtures of the respective cis and trans 477-thiopyran 1-oxides as determined by crystal structures when the 4-substituent is a methyl group <2005NCS165> the boat conformations are rather flattened, but the 4-benzyl compounds have planar thiopyran rings <2005NCS420>. 

Similar to the P450s, these reactions are often stereospecific and include hetero-atom oxidations, epoxidation, and oxidation of C-H bonds in allylic/benzylic compounds, alcohols, and indole [59]. 

Oxidation. This pentavalent iodine compound oxidizes primary or secondary alcohols to aldehydes or ketones in generally high ield (85-95%), Benzylic alcohols are oxidized more readily and also in high yield. Work up of the reactions involves conversion... 

Ce Compounds oxidize side chains of aromatic compounds effectively and selectively, methylene carbons at the benzylic positions being oxidized to carbonyl groups. Polymethy-lated aromatics generally are oxidized to a single aldehyde group. 

Compounds containing active hydrogen atoms (pK = 11-25) could be brominated when DBU was added dropwise into a mixture of substrate (phenylacetylene, diethyl butylmalonate, indene, or fluorene) and BrCClj in benzene (78CL73). Compounds with lower acidity (pK 29) exhibited no reaction. With more acidic derivatives (diethyl malonate and benzyl cyanide), oxidative dimerization also occurred. Oxidative dimerization also took place when BrCClj was added dropwise into a solution of active methylene compound and DBU in benzene. The ratio of the reaction products depended on the ratio of DBU and BrCCIj. 

Dihydroxycoumarin (55) underwent selective methylation (dimethyl sulfate) to the 7-methoxy derivative (56), which upon benzylation and oxidation (selenium dioxide), afforded the 4-formyl coumarin (74). Conversion to the acetal (75) occured upon treatment with triethyl orthoformate, and subsequent catalytic hydrogenation served the dual purpose of removal of the benzyl group and reduction of the coumarin double bond, to give (76). Hydride reduction of the derived acetate (77), followed by acidic workup, gave directly the furobenzofiiran (75) [presumably through the hydroxy aldehyde (75)]. Comparison of the spectra of racemic (75) with those of the naturally derived material showed the compounds to be identical. 

Other phosphoryl compounds which have been studied through their dipole moments are the vinyl- and substituted benzyl- diphenylphosphine oxides. 

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