Dichloromethane oxidation with

A ground mixture of iron(III) nitrate and HZSM-5 zeolite, termed zeofen , has also been used both, in dichloromethane solution and in solid state under MW irradiation conditions [101]. It has been suggested that the zeolite aids the reproducibility of the reaction but any other aluminosilicate support would probably be equally effective. Recent studies point out attractive alternatives that do not employ any of the solid supports in such oxidations with nitrate salts [102]. 

DMPO is more difficult to oxidize than PBN by about 0.2 V (Table 1) and is therefore expected to engage in spin trapping via its radical cation with greater difficulty, as found for the 0sCl6-4-N02-PBN reaction. Only acetate ion, tetramethylsuccinimide ion and triethyl phosphite gave the corresponding adducts upon oxidation with TBPA + in dichloromethane in the presence of DMPO, whereas fluoride ion gave the hydroxyl adduct. The latter was probably formed from water available from the unavoidable hydration shell around fluoride ion in its tetrabutylammonium salt. 

High yields (76-81%) of alcohols are also obtained by adding solutions of acyl chlorides in anhydrous dioxane or diethyl carbitol to a suspension of sodium borohydride in dioxane and brief heating of the mixtures on the steam bath [751], by stirring solutions of acyl chlorides in ether for 2-4 hours at room temperature with aluminum oxide (activity I) impregnated with a 50% aqueous solution of sodium borohydride (Alox) (yields 80-90%) [1014], by refluxing acyl chlorides with ether solutions of sodium trimethoxyborohydride [99], or by treatment of acyl chlorides in dichloromethane solutions with tetrabutylammonium borohydride at —78° [771]. A 94% yield of neopentyl alcohol was achieved by the reaction of trimethylacetyl chloride with tert-butylmagnesium chloride [324]. 

Oxidation of thiophene with m-chloroperbenzoic acid (MCPBA, 3-chloroperoxobenzoic acid) probably gives first unstable thiophene 1-oxide, and then thiophene 1,1-dioxide (Scheme 6.34a). 2,5-Diarylthio-phenes can be oxidized to the corresponding 1-oxides with 30% aqueous hydrogen peroxide in trifluoroacetic acid and dichloromethane. 

Another total synthesis of sufentanil has been described the cyclization of 2-(2-thienyl)ethylamine with allyl-trimethylsilane and formaldehyde gives 4-hydroxy-1-[2-(2-thienyl)ethyl]piperidine, which is oxidized with oxalyl chloride in DMSO/dichloromethane to 1-[2-(2-thienyl) ethyl]piperidin-4-one. The epoxidation of this compound by means of trimethylsulfonium iodide and the sodium salt of DMSO yields the spiro-epoxide, which is opened with... 

The formation of peracids as the effective oxidizing species has often been proposed for oxidations with sodium percarbonate in the presence of organic acids or acid anhydrides30-32. It was observed that at room temperature and in dichloromethane as solvent, the addition of acetic anhydride induced the epoxidation by sodium perborate of mono-, di- and trisubstituted alkenes, including a,/i-unsaturated ketones in a slightly exothermic reaction33 (equation 6). 

Studies of the reactions of quinoxaline N-oxides under Reissert reaction conditions have led to some very interesting and unusual results. Thus, treatment of quinoxaline IV-oxide with PhCOCl/KCN in methanol or water under standard Reissert conditions gave 6-chloroquinoxaline as the major product (ca. 45%), and only small amounts of the desired 2-cyanoquinoxaline. Use of 3 equivalents of TMSCN in place of KCN and dichloromethane as solvent, however, gave 2-cyanoquinoxaline in 72% yield. When 2,3-diphenylquinoxaline iV-oxide was treated with 1 equivalent of PhCOCl in the presence of 3 equivalents of either KCN or TMSCN a mixture of products was always obtained irrespective of the solvent used. The most interesting of these products was the ring cleaved compound 1. 

Dihydro-l,3-dioxepins 47 have been oxidized with w-chloroperbenzoic acid to give 4,5-dihydroxylated products. The product formation depends on the solvent used for oxidation. In dichloromethane (DCM), 4-acyloxy-5-hydroxydioxepanes 21 were formed whereas, the same reaction in MeOH afforded 5-hydroxy 4-methoxydioxepanes 48 (Scheme 2) <2001AGE177>. 

For example, PTV film was fabricated as follows. Polymerization of a sulphonium monomer, 2,5-thienylene bis (methylene-dimethyl-sulphonium chloride) was carried out in a methanol-water mixture at -20°C by adding a methanol solution of tetramethyl-ammonium hydroxide. The reaction was quenched by an addition of hydrochloric acid. A yellow precipitate (precursor polymer) appeared as the solution was warmed to room temperature. The precipitated precursor polymer was completely soluble in dich-loromethane. A precursor polymer thin film was obtained by spin-coating of the dichloromethane solution of the precursor polymer onto a fused silica glass substrate under inert atmosphere to prevent oxidation with air. The film was heated at 200-250°C in a vacuum of 10"2 Torr for 5 hours, to give a tough, flexible PTV film. The resulting PTV thin film was chemically stable in air. 

Formyl derivative 362 was prepared when 9-hydroxymethylpyrido-pyrimidin-4-one 361 in dichloromethane was added to a cooled mixture of oxalyl chloride and dimethyl sulfoxide at - 50°C/ - 60°C in the presence of triethylamine. 9-Formyl derivative 362 was oxidized with silver nitrate in aqueous ethanol, and after 15 minutes of stirring the reaction mixture was treated with aqueous potassium nitrate for 2 hours at ambient temperature to give pyrido[ 1,2-a]pyrimidine-9-carboxylic acid 363 (91EUP453042). 

Diaryl tellurides undergo facile ligand-transfer oxidations with [bis(acyl-oxy)iodo]arenes in chloroform to give stable diaryltellurium dicarboxylates 12 (Scheme 7) [23]. Similar ligand-transfer oxidations of triarylbismuthanes and triarylstibanes with BAIB in dichloromethane leading to Bi(V) and Sb(V) diacetates 13 and 14 have also been reported [24,25]. The triarylbismuth diacetates were employed for high yield Cu(II)-catalyzed arylations of a series of aryl-amines [24]. 

Condensed dithiatriazepine 160 was rapidly and cleanly converted into dithiazolc-.Y-oxide 150 by oxidation with w-chloroperoxybenzoic acid (MCPBA) in dichloromethane at room temperature (Equation 45) <1998CC1207>. 

PMB ethers can be cleaved oxidatively with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ)11 in dichloromethane/water tor with cerium ammonium nitrate (CAN) in acetonitrile/water.12 Many other protecting groups such as esters, isopropylidene acetals, benzyl ethers, allyl ethers and f-butyldiphenyl silyl (TBDMS) ethers are stable to these conditions (Scheme 2.4). The cleavage reaction, with DDQ is initiated with a single-... 

Primary aliphatic amines, on oxidation with IOB in dichloromethane or water, were converted into nitriles in moderate yield, e.g. hexylamine was dehydrogenated to hexanenitrile (57%), after 3 days stirring at room temperature with 2 equivalents of IOB. Similarly benzylamine gave benzonitrile with one equivalent of IOB, the main... 

In the earliest authentic halocarbon complex (1982), o-diiodobenzene was found to chelate to cationic Ir(III) as shown in diagram (5)." An earlier proposed example proved to be misidentified when the crystal structure was carried out. To be stable, any such complex must resist oxidative addition, hence the use of an oxidation state, Ir(III), that is only oxidized with difficulty. The normally rather weakly basic halocarbon lone pairs are often reluctant to bind, but chelation and involvement of the least electronegative hahde, iodine, favor binding as does the cationic character of the complex. A series of such complexes was soon found, including complexes of fr(I)" and a series of weakly bound dichloromethane complexes for certain systems." These solvento complexes can be very labile and so find use as precursors for binding of other weakly basic hgands. Even fluorocarbon complexes proved viable." A review of the area is available. It now seems... 

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