Synthesis cerium

An ester group can also activate side-chain alkyl for halogenation, and such pyrrolylalkyl halides have been used extensively in synthesis. Cerium(IV) triflate in methanol can be used for the analogous introduction of methoxide onto an alkyl side chain. 

Within the cubane synthesis the initially produced cyclobutadiene moiety (see p. 329) is only stable as an iron(O) complex (M. Avram, 1964 G.F. Emerson, 1965 M.P. Cava, 1967). When this complex is destroyed by oxidation with cerium(lV) in the presence of a dienophilic quinone derivative, the cycloaddition takes place immediately. Irradiation leads to a further cyclobutane ring closure. The cubane synthesis also exemplifies another general approach to cyclobutane derivatives. This starts with cyclopentanone or cyclohexane-dione derivatives which are brominated and treated with strong base. A Favorskii rearrangement then leads to ring contraction (J.C. Barborak, 1966). 

The greater lability of 1-benzothiepin 1-oxides, compared to the parent compounds, may lead to differences in chemical behavior. Thus, treatment of the tricarbonyliron complex of 1-benzo-thiepin 1-oxide (8, X = SO) with ammonium cerium(IV) nitrate in acetone at — 30 °C leads, with the loss of sulfur monoxide, to naphthalene. In contrast, the iron ligand can be removed selectively from the corresponding 1-benzothiepin by ammonium cerium(IV) nitrate.23 92 For the synthesis of 1-benzothiepin 1-oxide, see Section 2.1.4.1,... 

The first compound of this series, CeSI, was reported by Carter (68) in 1961, and later discussed by Dagron (93). It was obtained by the reaction of iodine with cerium sulfide at 430 C, or by direct synthesis from the elements at 500°C. This was the start of a detailed investigation of this group of compounds mainly by Dagron and co-workers. The present situation is presented in Table VII. No scandium compounds are known thus far, and the same is true for selenium and tellurium halides of these elements. 

Results and Discussion. Of the 12 samples of starch graft copolymer synthesized, half were hydrolyzed to anionic polyelectrolytes. Synthesis data on these 6 samples are given in Table 2. These particular samples were chosen for hydrolysis because the samples can be intercompared to see the effect of synthesis variables on ultimate product properties. Samples 5, 8, and 11 have the same mole ratio of cerium ion to starch backbone, N, in their reaction mixture. Samples 7, 8, and 9 all have the same refctable mass per starch molecule,... 

Sardar, K., Playford, H.Y., Darton, R.J., Barney, E.R., Hannon, A.C., Tompsett, D., Fisher, J., Kashtiban, R.J., Sloan, J., Ramos, S., Cibin, G. and Walton, R.I. (2010) Nanocrystalline cerium-bismuth oxides synthesis, structural characterization, and redox properties. Chemistry of Materials, 22 6191-6201. 

A short total synthesis of racemic 7-epi-/3-bulnesene was achieved, in which vinyl cerium 23 was used for the introduction of a three-carbon unit to a ketone 22 to afford tertiary alcohol 24, the substrate for the key intramolecular cyclization/Claisen rearrangement sequence (Scheme 8).14... 

A diastereoselective synthesis of vicinal diamines has been described79. The aldehydes 56 derived from chiral amino acids 55 were converted into the A-benzylimines 57 and the latter were treated with organometallic reagents R2M in the presence of cerium(III)... 

Sridharan V, Maiti S, Menendez JC (2009) A very efficient cerium(IV) ammonium nitrate catalyzed, four-component synthesis of tetrahydropyridines and its application in the concise generation of functionalized homoquinolizine frameworks. Chem Eur J 15 4565 572... 

The reasoning which led the author to make this first shot in the dark regarding the usefulness of combinations of solid compounds as ammonia catalysts was as follows If we assume that a labile iron nitride is an interminate in the catalytic ammonia synthesis, every addition to the iron which favors the formation of the iron nitride ought to be of advantage. In other words, the hypothesis was used that surface catalysis acts via the formation of intermediate compounds between the catalyst and one or more of the reactants. An experimental support for this theory was the fact that a stepwise synthesis via the formation and successive hydrogen reduction of nitrides had been carried out with calcium nitrides (Haber), and cerium nitrides (Lipski). Later, the author found molybdenum nitride as being the best intermediate for such a stepwise synthesis. 

Sridharan V, Avendano C, Menendez JC (2008) New findings on the cerium(IV) ammonium nitrate catalyzed Povarov reaction stereoselective synthesis of 4-alkoxy-2-aryl-l,2,3,4-tetrahydroquinoline derivatives. Synthesis 1039-1044... 

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