Cerium acetate nitrate

CAN = cerium-ammonium nitrate, (NH4)jCe(N03)5 products are benzylic acetates. 

V,/V-Bis(trifluoromethyl)hydroxylamine (5) is oxidized with potassium permanganate in acetic acid to an interesting free-radical compound, bis(trifluoromethyl)nitroxid-A7-yl(6), a pink-violet gas which condenses to a deep brown-violet liquid.246 Various oxidizing agents are effective in the oxidation of 5 to the corresponding nitroxyl 6.247 The best appears to be cerium(IV) salts either in the solid state or in aqueous acid solution.247 Efficient oxidation processes have been developed using aqueous potassium persulfate solutions, or electrochemical oxidation with cerium(III) nitrate and sodium nitrate in dilute nitric acid.247... 

The oxidation reaction of alkylaromatic compounds with cerium-ammonium nitrate in acetic acid medium is crucial for understanding the problem (Baciocchi, Rob, Man-dolini 1980) ... 

Yamashiro et al. 1972), boron trifluoride etherate in acetic acid (Schnabel et al. 1971), trimethylsylil triflate (Schmidt et al. 1987), trimethylsilyl perchlorate (Vorbrueggen Krolikiewicz 1975), and, most frequently, trifluoroacetic acid (Farowicki Kocienski 1995 and references therein). Deprotection of the /-HOC group under neutral conditions was not described until recently, yet it is highly desirable. Now it has been found that the tert-butoxycarbonyl protecting group for amines, alcohols, or thiols is removed efficiently (90-99% yield) with use of 0.2 equivalent of cerium ammonium nitrate in acetonitrile at 80°C (Hwu et al. 1996) ... 

Hwu et al. have examined the dependence of the metal oxidant on the mode of reactivity in silicon-controlled allylation of 1,3-dioxo compounds [95JOC856]. The use of manganese(III) acetate furnished the dihydrofuran product 22 only. On the other hand, use of cerium(IV) nitrate resulted in the formation of both acyclic (23) as well as the cyclized compound, with the product distribution dependent on the nature of the allylsilane. Facile synthesis of dihydrofurans by the cerium(IV) mediated oxidative addition of 1,3-dicarbonyl compounds to cyclic and acyclic alkenes has also been reported [95JCS(P1)187]. 

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-... 

Two short syntheses of P-lapachone from readily available naphthols and 3-methylbut-2-enal via a mild phenyl-boronic acid mediated cyclization to 2//-chromenes have been reported. Catalytic hydrogenation of 2H-chromenes with H /Pd-C in ethyl acetate afforded the corresponding naturally occurring chromanes (72) and (73). Oxidation of the adequate chromane with an excess of cerium ammonium nitrate (CAN) furnished P-lapachone in 62% yield [153]. 

Ammonium cerium(IV) nitrate or cerium(IV) sulfate will catalyze the selective oxidation of secondaiy alcohols with sodium bromate as cooxidant, in this case remote C—C double bonds interfere, but 1,2-diols are not cleaved. It has been found that sodium bromite in aqueous acetic acid will act as a selective oxidant for secondary mary diols without the need for other catalysts (Scheme 21). ... 

The 2,5-dihydro-l,2,3-triazines 20, obtained by reaction of 1,2,3-triazines 19 with ketene silyl acetals or silyl enol ethers in the presence of 1-chloroethyl chloroformate, can be readily oxidized and hydrolyzed with ammonium cerium(lV) nitrate (CAN) in acetonitrile/water to afford 5-substituted 1,2,3-triazines 21.3 64... 

Small batches ( 10 g) of powders were prepared by the glycine-nitrate process (GNP) [5], Appropriate amounts of metal salts (barium-, cerium-, yttrium-, and zirconyl nitrates, ammonium cerium [IV] nitrate, and barium acetate were [Alfa Aesar, Ward Hill, MA]) and glycine were dissolved in deionized water. The solution was heated on a hot plate in a stainless steel beaker until a sufficient amount of solvent had evaporated allowing the precursor to ignite. The resulting ash was sieved (100-mesh) and calcined for 20 min to 30 min at 1,200°C to produce the desired single-phase perovskite. Additional material was obtained commercially (Praxair). The following compositions were synthesized ... 

Initially, sulfuric acid was used to initate the Borsche—Drechsel cyclization. However, Perkin found that acetic acid provided cleaner products. Recently, other reagents—such as cerium ammonium nitrate (CAN) and the more environmentally friendly acidic ionic liquids —have been used to catalyze the ring formation. It should be noted that people have found it difficult to promote the cyclization when there are substituents at the ortho-position of the phenylhydrazine. This difficulty becomes more pronounced when both the hydrazine and the cyclohexanone have a-substitution This difficulty usually leads to low yields compared with other methods of forming the carbazole. 

To a reaction tube charged with cerium ammonium nitrate (68 mg, 0.125 mmol, 0.25 mmol of NH4, 1 equiv.) and copper trifluoroacetate hydrate (14.5 mg, 0.05 mmol, 20 mol%) was added a solution of acetaldehyde (1 mmol) and H2O (135 iL, 7.5 mmol, 30 equiv.) in DMF (3 mL) imder argon (1 atm). The reaction mixture was then stirred at 80°C for 12 h. After cooling to room temperature, the mixture was diluted with ethyl acetate, washed with saturated sodium bicarbonate, water and brine, dried over anhydrous sodium sulfate, and concentrated in vacuo to give dark residue, which was purified by flash chromatography (using petroleum ether and ethyl acetate as the effluent) on silica gel to afford the 5-diarylpyridine product. 

An equimolar amount of 30%-H2O2 added dropwise with stirring to phenyl vinyl sulfide in acetic anhydride, stirring continued 5-6 hrs., and allowed to stand overnight phenyl vinyl sulfoxide. Y 82%. F. e. s. A. V. Sviridova, V. I. Laba, and E. N. Prilezhaeva, Zh. Org. Khim. 7, 2480 (1971) C. A. 76, 72158 with N-chloro-nylon-66 in methanol-benzene or water-dioxane s. Y. Sato, N. Kunieda, and M. Kinoshita, Chem. Lett. 1972, 1023 (Eng) C. A. 77, 164179 with ammonium cerium(IV) nitrate, mostly diaryl sulfoxides, s. T.-L. Ho and C. M. Wong, Synthesis 1972, 561. 

A variety of cerium(rV) salts were evaluated as alternatives to manganese(III) acetate in aromatic nitromethylations (Kurz and Ngoviwatchai, 1981). While CAN effected high-yield conversions, persistent side reactions were attributed to the presence of cerium(III) nitrate. In contrast, cerium(IV) acetate generated in situ gave high 5uelds of nitromethylation products free of side-products. 

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