Oxidation benzylic, with

Diphenylthiirene 1-oxide reacts with hydroxylamine to give the oxime of benzyl phenyl ketone (79JA390). The reaction probably occurs by addition to the carbon-carbon double bond followed by loss of sulfur monoxide (Scheme 80). Dimethylamine adds to the double bond of 2,3-diphenylthiirene 1,1-dioxide with loss of sulfur dioxide (Scheme 81) (75JOC3189). Azide ion gives seven products, one of which involves cleavage of the carbon-carbon bond of an intermediate cycloadduct (Scheme 81) (80JOC2604). 

A cursory inspection of key intermediate 8 (see Scheme 1) reveals that it possesses both vicinal and remote stereochemical relationships. To cope with the stereochemical challenge posed by this intermediate and to enhance overall efficiency, a convergent approach featuring the union of optically active intermediates 18 and 19 was adopted. Scheme 5a illustrates the synthesis of intermediate 18. Thus, oxidative cleavage of the trisubstituted olefin of (/ )-citronellic acid benzyl ester (28) with ozone, followed by oxidative workup with Jones reagent, affords a carboxylic acid which can be oxidatively decarboxylated to 29 with lead tetraacetate and copper(n) acetate. Saponification of the benzyl ester in 29 with potassium hydroxide provides an unsaturated carboxylic acid which undergoes smooth conversion to trans iodolactone 30 on treatment with iodine in acetonitrile at -15 °C (89% yield from 29).24 The diastereoselectivity of the thermodynamically controlled iodolacto-nization reaction is approximately 20 1 in favor of the more stable trans iodolactone 30. 

This is consistent with the observed products of oxidation, i.e. benzyl alcohol, benzaldehyde and benzoic acid and with the observed oxidation of cyclohexane. Radical-cations are, however, probably formed in oxidation of napthalene and anthracene. The increase of oxidation rate with acetonitrile concentration was intepreted in terms of a more reactive complex between Co(III) and CH3CN. The production of substituted benzophenones at high CH3CN concentration indicates the participation of a second route of oxidation. 

Reduction of 1-benzyl-3,4-dibromophospholan oxide (125) with tri-chlorosilane, followed by debromination, gave 1-benzylphosphole. Determination of the molecular structure by X-ray analysis showed slight puckering of the ring with retention of pyramidal configuration at phosphorus. ... 

Compound 56 is the first branch point intermediate in the analog syntheses, furnishing 90 upon oxidative cyclization with MnC>2 and deprotection with Mgl2. Intermediate 56 was also benzylated to protect the C5,C5 -naphthols in preparation for ester hydrolysis, which provided the next key branch point intermediate, bisacid 91. Ester hydrolysis here with aqueous base was surprising facile relative to intermediate 62, en route to (+)-calphostin D (Scheme 7.14). Presumably, the smaller C7,C7 -groups alleviate the steric gearing that hinders the reactivity of the C3,C3 -esters. 

Two reports have been made of the preparation of P-chiral phosphine oxides through reaction of chiral f-butylphenylphosphine oxide treated with LDA and electrophiles. The electrophiles included aldehydes,355 ketones,355 and benzylic-type halides.356 Optically active a-hydroxyphosphonate products have also been generated from aldehydes and dialkyl phosphites using an asymmetric induction approach with LiAl-BINOL.357... 

In SL-PC, a catalyst is supported on a solid matrix in the form of the film of a nonvolatile liquid phase adsorbed on the solid. The catalytic film can be, for example, a molten salt or a molten oxide (e.g., Deacon s catalyst (CUCI2/KCI) used to oxidize HCl with oxygen for the chlorination of ethylene in the synthesis of vinyl chloride. Figure 6.1 V2O5 for the oxidation of sulphurous to sulphuric anhydride). Alternately, it can be a liquid phase (e.g., ethylene glycol, PPh3, butyl benzyl phthalate, etc.) that contains a soluble catalytic species such as a metal complex. 

Table 2. Benzyl alcohol oxidation reaction with different catalytic systems ...

The reactivities of [Ru "(0)(14-TMC)(X)]"+ and its related 15-TMC, 16-TMC, and CRMes coi lexes with organic substrates have also been examined. " " In contrast to polypyridyl Ru =0 species, these macrocyclic Ru =0 complexes are weak oxidants. They oxidize benzyl alcohol to benzaldehyde but do not react with alkenes at room temperature. The lower oxidizing ability of these systems than the polypyridyl systems is due to their lower values. However, [Ru (0)(H20)(N202)](C104)2, which has a higher H value, is able to catalyze the oxidation of norbornylene, styrene, and cyclooctene by PhlO. " ... 

This heme-dependent enzyme [EC 1.11.1.14], also known as diarylpropane peroxidase, diarylpropane oxygenase, and ligninase I, catalyzes the reaction of 1,2-bis(3,4-dimethoxyphenyl)propane-l,3-diol with hydrogen peroxide to produce veratraldehyde, l-(3,4-dimeth-ylphenyl)ethane-l,2-diol, and four water molecules. The enzyme brings about the oxidative cleavage of C—C bonds in a number of model compounds and also oxidizes benzyl alcohols to aldehydes or ketones. 

Methazolamide Methazolamide, N-(4-methyl-2-sulfamoyl-l,3,4-thiadiazol-5-yliden) acetamide (21.2.3), is made by an intermediate product of acetazolamide synthesis— 2-acetylamino-5-mercapto-l,3,4-thadiazol (9.7.3). This is benzylated with benzylchloride at the mercapto group, forming 2-acetylamino-5-benzylthio-l,3,4-thiadiazole (21.2.1). Further methylation of the product with methyl iodide leads to the formation of N-(4-methyl-2-benzylthio-l,3,4-thiadiazol-5-yliden)acetamide (21.2.2). Oxidation and simultaneous chlorination of the resulting product with chlorine in an aqueous solution of acetic acid, and reacting the resulting chlorosulfonic derivative with ammonia gives (21.2.3) [5-7]. 

This method has been extended to include 1,3-diarylthioureas which are benzylated and then treated with phenylisocyanate to give S-benzylisothiobiurets (252). Oxidative debenzylation with... 

AUtyl, allyl, benzyl and cycloalkyl sulfones can be converted to aldehydes or ketones in good to excellent yields by treatment with n-BuLi followed by BTSP. Carbonyl-O labeling was achieved in situ by using oxidative desulfonylation with (Me3Si)2 02 (equation 50) . 

The oxidation of benzaldoxime with perchloryl fluoride (FClOj) has been reported [29 a) to give a complex mixture in which benzaldoxime benzoate and diphenyl oxadiazole are the main products. Sodium nitrohydroxamate [Na2(02NN0)] has been reported [99b) to oxidize benzyl chloride to a mixture of compounds from which benzyl alcohol, benzaldehyde, benzoic acid, 3,4,5-triphenylisoxazole, benzyl-ethyl-ether, phenylnitromethane and diphenyloxadiazole have been isolated. 

A copper(O) complex, electro-generated from Cu(acac)2, is able to undergo an oxidative addition with benzyl and allyl bromides. Further reduction leads to the coupling products bibenzyl and 1,5-hexadienes Methyl-3-hexene-l,6-dicarb-oxylate can be prepared from butadiene and CO by electroreduction if di-Fe dicyclopentadienyl tetracarbonyl is used as redox catalyst Electro-generated low-valent tungsten species are able to reductively dimerize benzaldehyde to stilbene according to Eq. 83. The reduction potential was controlled at the third wave of the WClg catalyst (V = -1900 mV/SCE)... 

Dialkyl (or aryl) analogs with unlike substituents are obtainable by this last route thus, treatment of phenylthioacetamide-5-oxide (17) with thiobenzamide (18) gave a product that was formulated as 5-benzyl-3-phenyl-1,2,4-thiadiazole (19),16 but was recently recognized28 to be the 3-benzyl-5-phenyl isomer 21. It does not, therefore, arise by... 

Kinetic and mechanistic investigations on the o-xylene oxidation over V205—Ti02 catalysts were carried out by Vanhove and Blanchard [335, 336] using a flow reactor at 450°C. Possible intermediates like o-methyl-benzyl alcohol, o-xylene-a,a -diol, toluic acid and phthalaldehyde were studied by comparing their oxidation product distribution with that of toluene. Moreover, a competitive oxidation of o-methylbenzyl alcohol and l4C-labelled o-xylene was carried out. The compounds investigated are all very rapidly oxidized, compared with o-xylene, and essentially yield the same products. It is concluded, therefore, that these compounds, or their adsorbed forms may very well be intermediates in the oxidation of o-xylene to phthalic anhydride. The ratio in which the partial oxidation products are formed appears to depend on the nature of the oxidized compounds, i.e. o-methylbenzyl alcohol yields relatively more phthalide, whereas o-xylene-diol produces detectable amounts of phthalan. This... 

It is noteworthy that Pt02(PPh3)2 can oxidize benzyl to benzoic anhydride with 55% yield by inserting one oxygen atom between the two carbonyl groups.195... 

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