Cesium deficiency

As cesium invariably accompanies potassium only in traces in the biosphere, it is unlikely that any symptoms of cesium deficiency would be observed, if sufficient potassium is taken up. 

Acute effects in animals and humans resulting from a cesium deficiency or related to high cesium intake have not been reported. A high intake of cesium is rapidly excreted via the kidneys (Yamagata etal., 1966), and consequently no reports have been made on any chronic effects due to stable cesium intake. Neither have any mutagenic, carcinogenic or teratogenic effects of stable cesium been either studied or described. 

The similar cross-coupling reaction of compounds 1 with aryl iodides was less sensitive to the electronic nature of the substrates than that with aryl triflates i.e., electron-deficient 4 -iodoacetophenone and electron-rich 4-iodoanisole afforded the cross-coupling products in 96% and 55% yields, respectively (Scheme 29) [45]. The addition of cesium salts improved the product yields considerably. Aryl bromides were less efficient than aryl iodides, and addition of cesium salts was necessary to improve the product yields. 

Alkali metals (K, Rb, Cs) behave similarly and sometimes one is accumulated preferentially when another is deficient. A similar case is made for Sr and Ca (Whicker and Schultz 1982a). The most important alkali metal isotope is Cs because of its long physical half-life (30 years) and its abnndance as a fission prodnct in fallout from nuclear weapons and in the inventory of a nuclear reactor or a fuel-reprocessing plant. Cesium behaves much like potassium. It is rapidly absorbed into the bloodstream and distribnted throughout the active tissues of the body, especially muscle. The P and y radiation from the decay of Cs and its daughter, Ba, result in essentially whole-body irradiation that harms bone marrow (Hobbs and McClellan 1986). 

A cesium salt CsfAuFg] is obtained if a slight deficiency of CsF is mixed with the above XegFn salt and heated to 110°C, when XeFe is evolved. 

It has been demonstrated that TMS iodide (in combination with cesium fluoride) or TMS triflate in various solvents (THF, MeCN, HMPA) are excellent reagents to promote the generation of azomethine ylids from A-methoxymethyl-A-(trimethylsilylmethyl)aIkyl-amines and their cycloaddition to electron deficient alkenes with yields ranging from moderate to nearly quantitative. The geometry of the double bond in the alkene is preserved in the cycloadduct.410... 

This instant invention represents an improvement in the Ullman coupling reaction. This investigation represents the first general method for coupling electron deficient phenols and unactivated aryl halides (1,2,3,4). The basis of the improvement lay in the high solubility of (CuOTf)2 benzene and cesium phenolate or copper phenolate in the reaction solvent, toluene. 

Under the Larock s reaction conditions, where bases like pyridine A7-oxide and cesium fluoride are in deficient proportions, transformafiMi of the intermediate A into... 

Weidner ef alP described a one-pot Smiles rearrangement method for the synthesis of various aminoquinolines from the corresponding hydroxyquinolines and showed that the tendency for the conversion depends on the electron-deficient nature of the quinolines. In a specific example, the reaction of 15 with (i) 2-bromo-2-methylpropionamide, 3 equiv. each of NaH and cesium carbonate in dioxane at reflux for 16 h and (ii) N-methylpyrrolidinone (NMP), l,3-dimethyl-3,4,5,6-tetrahydro-2(l//)-pyrimidinone (DMPU) (10 1 ratio) and 1 equiv. of NaH at 150 C for 72 h afforded the amine 16. 

In a related ARCIS process, the Pd-based cross-coupling of o-bromobenzyl alcohols with o-iodobiphenyls under basic conditions (cesium carbonate) with palladium catalysis allows the preparation of several highly substituted triphenylenes. The use of an electron-deficient phosphine ligand is sufficient to assure the formation of two C-C bonds at the expense of a C-C and a C-H bond [71b], Another approach for the synthesis of triphenylenes involves the [2+2+2] trimeiization of benzynes, generated in situ from benzoic acids [71c]. The cooperative Pd(II)/Cu(II) catalytic system was found to be suitable for ortho C-H bond activation in benzoic acids followed by decar-bonylation (Scheme 22.49). 

In contrast to transition-metal molecular clusters, the alkali-metal suboxides are stable only in the solid state. As described in Table 4.4, these clusters decompose at temperatures rather below the melting point of the metals. The stability of these species appears to be relatively precarious. It is very probable that the stabilization of this class of extreme electron-deficient compounds is possible only at relatively low temperature and in strong reducting media such as the alkali-metals rubidium or cesium. 

The electron-deficient alkene 75 did not favor intramolecular [3 + 2] cycloaddition and instead gave rearranged diazoacetate 76 in 64% yield upon heating at 125 °C. Copper(I) trifiate-catalyzed decomposition of 75 gave a mixture of compounds and only 14% of cyclopropane system 77 (eq 18) was isolated. Finally, the authors showed that desilylation of these silabicyclic compounds can be achieved using cesium fluoride in wet THF to provide fraw5-l,2-cyclopropanes (eq 19). ... 

The conversion of diazo compounds into gm-difluoroalkenes is an attractive route to the synthesis of these compounds (Scheme 7.105) [168]. The reactions are catalyzed by a catalytic amount of copper salt with an equimolar amount of cesium fluoride as an additive. It is noteworthy to point out the copper loading in this example is significantly lower than other copper-catalyzed fluorinations. In general, diaryl diazomethanes bearing electron-donating groups afforded lower yields than electron-deficient arenes. 

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