Oxidation methyl phenyl

Komori and Nonaka132,133 electrochemically oxidized methyl, isopropyl, n-butyl, isobutyl, r-butyl and cyclohexyl phenyl sulfides (108) and cyclohexyl p-tolyl sulfide (109) to their sulfoxides using a variety of polyamino acid-coated electrodes to obtain the range of e.e. values shown in parentheses. The highest enantiomeric purities were obtained using an electrode doubly coated with polypyrrole and poly(L-valine), an electrode which also proved the most durable of those prepared. 

Oxidation of dibenzyl and methyl phenyl sulphides by lead tetraacetate in acetic acid was also reported127. 

In the course of this study, the authors determined /Lvalues for dibenzyl, methyl phenyl, methyl p-nitrophenyl, di-p-tolyl, di-isopropyl and tetramethylene sulphoxides and for diethyl, dipropyl and dibutyl sulphites. The /Lscales are applied to the various reactions or the spectral measurements. The /Lscales have been divided into either family-dependent (FD) types, which means two or more compounds can share the same /Lscale, family-independent (FI) types. Consequently, a variety of /Lscales are now available for various families of the bases, including 29 aldehydes and ketones, 17 carboxylic amides and ureas, 14 carboxylic acids esters, 4 acyl halides, 5 nitriles, 10 ethers, 16 phosphine oxides, 12 sulphinyl compounds, 15 pyridines and pyrimidines, 16 sp3 hybridized amines and 10 alcohols. The enthalpies of formation of the hydrogen bond of 4-fluorophenol with both sulphoxides and phosphine oxides and related derivatives fit the empirical equation 18, where the standard deviation is y = 0.983. Several averaged scales are shown in Table 1588. 

The oxidation of sulphoxides containing aromatic groups such as methyl phenyl sulphoxide and diphenyl sulphoxide proceeds at 20 30°C in low yields in the presence of sulphuric acid as solvent12. However the product is usually contaminated with compounds containing nitro groups in the aromatic nucleus, as indicated in equation (6). 

The base catalysed autoxidation of dimethyl sulphoxide and methyl phenyl sulphoxide at 80 °C produces low quantities of methanesulphonic acid in both cases and benzenesul-phonic acid in the latter case189 (equation 71 and 72). There is no evidence of sulphone formation in either reaction. Dimethyl sulphoxide oxidation to methanesulphonic acid also occurs in the presence of trace quantities of acid and oxygen. Again the reaction would not be synthetically useful190. 

The oxidative dimerization of the anion of methyl phenyl sulfone (from a Grignard reagent) in ethereal solution in the presence of cupric chloride in 5% yield has been reported47. Despite the reported48 poor stability of the a-sulfonyl C-centered radicals, Julia and coworkers49 provoked the dimerization (in 13 to 56% yields) of the lithiated carbanion of alkyl phenyl sulfones using cupric salts as oxidants. The best results are obtained with cupric triflates in THF-isobutyronitrile medium (56% yield for R = H). For allyl phenyl sulfones the coupling in the 3-3 mode is predominant. 

Chlor-phenyl)- 693 2-(4-Chlor-phenyl)- -1-oxid 693 2-(2-Hydroxy-4-methyl-phenyl)- 693 2-(2-Hydroxy-5-methyl-phenyl)- -1-oxid 693 2-(4-Methoxy-phenyl)- 693 2-(4-Methoxy-phenyl)- -1-oxid 693... 

It is also appropriate to observe the substantial difference in ease of oxidation between phenyl and methyl isocyanide complexes, which has obvious chemical implication. This may perhaps be rationalized on the basis that phenyl isocyanide is a better 7r-acceptor than methyl isocyanide. This conclusion had previously been reached by infrared studies (see Section II). 

Sulfoxides such as methyl phenyl sulfoxide 1898 are readily reduced by hexa-methyldisilthiane 601 to give sulfides such as methyl phenyl sulfide 1899 in 90% yield, sulfur, and HMDSO 7 [108-110]. Analogously, the S-oxide of diethylsulfide... 

Organic hydroperoxides have also been used for the oxidation of sulphoxides to sulphones. The reaction in neutral solution occurs at a reasonable rate in the presence of transition metal ion catalysts such as vanadium, molybdenum and titanium - , but does not occur in aqueous media . The usual reaction conditions involve dissolution of the sulphoxide in alcohols, ethers or benzene followed by dropwise addition of the hydroperoxide at temperatures of 50-80 °C. By this method dimethyl sulphoxide and methyl phenyl sulphoxide have been oxidized to the corresponding sulphone in greater than 90% yields . A similar method for the oxidation of sulphoxides has been patented . Unsaturated sulphoxides are oxidized to the sulphone without affecting the carbon-carbon double bonds. A further patent has also been obtained for the reaction of dimethyl sulphoxide with an organic hydroperoxide as shown in equation (19). 

The first examples of mononuclear disulfur and diselenium complexes of platinum have been described.330 Reduction of the sterically hindered complex trans- PtC 2( P M e2A r)2] (Ar = 2,4, 6-tris[bis(trimethylsilyl)methyl]phenyl, 2,6-bis[bis(trimethylsilyl)-methyl]-4-[tris(trimethylsilyl) methyl]-phenyl) with lithium naphthalide in THF solution affords the platinum(0) species [Pt(PMe2Ar)2]. Oxidative addition of elemental sulfur or selenium yields the dichalcogenatoplatinum(II) complexes of the type [PtE2(PMe2Ar)2] (E = S, Se) containing a unique PtE2 ring system. The complexes are stable to air in the solid state, but slowly decompose in solution after several days at room temperature. 

Tagat, J.R., Steensma, R.W., McCombie, S.W. et al. (2001) Piperazine-based CCR5 antagonists as HIV-1 inhibitors. II. Discovery of 1 - [(2,4-dimethyl-3-pyridinyl)carbonyl]-4- methyl-4- [3 (S)-methyl-4- [ 1 (5)- [4-(trifluoro- methyl)phenyl]ethyl]-l-piperazinyl]-piperidine Nl-oxide (sch-350634), an orally bioavailable, potent CCR5 antagonist. Journal of Medicinal Chemistry, 44 (21), 3343-3346. 

The reaction of a highly crowded 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl-dihydrostilbine (TbtSbE ) with elemental sulfur, in the presence of nitrile oxides, results in the formation of [2 + 3] cycloaddition reaction products of a thioxostil-bine TbtSb = S and a dithioxostiborane TbtSb(S) = S (363). 

Thioanisole, oxidation, by dinitrogen tetroxide, 46,80 by hydrogen peroxide, 46, 80 by lead tetraacetate, 46, 80 reaction with sodium metaperiodate to form methyl phenyl sulfoxide, 46,78... 

Run no. pH Conv. (mol%) Styrene oxide Methylated diol Diol Benzaldehyde Phenyl acetaldehyde Others... 

Methyl-3-penten-2-one. See Mesityl oxide Methyl-4-(phenylthio)phenyl sulfoxide,... 

The oxidation of methyl phenyl sulfide using fresh PWAA gave methyl phenyl sulfone in 97% yield. In the repeated use of recovered catalyst, the yields of sulfone in runs 2 to 5 ranged from 82 to 88%. The activities of recovered catalysts were somewhat reduced. The deactivation may be caused by catalyst pulverization or degradation of the PW12O403- species. While the reusability and stability of the catalyst should be improved, this concept would be useful for the creation of sophisticated solid catalysts. After Ikegami s reports, Neumann and coworkers [140] applied this strategy to the development of alkylated polyethyleneimine/POM synzymes. 

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