Sodium triphenylmethyl derivatives

This reaction has been used to make crystalline triphenylmethyl derivatives that have been characterized by X-ray structure determinations,22 and a technique has been developed for the reduction of hydrocarbons by liquid cesium activated by ultrasound irradiation in the presence of ethers such as diglyme.23 The blue solutions obtained when cesium metal is dissolved in THF in the presence of [18]-crown-6 have been used to metallate a series of 1,4- or 1,5-hexadienes. The organocesium compounds have not been isolated but they have been identified by derivatization by carbonation and trimethylsilylation.24 Substituted cyclopentadienyl derivatives of sodium have also been synthesized by this method.25... 

Schlenk and Marcus in 1914 found that triphenylmethyl chloride reacted with sodium amalgam in dry ether solution, when the operation was carried out in an atmosphere of nitrogen. The resulting compound, sodium triphenylmethyl, was a brick-red mass, decomposed by moisture or carbon dioxide. Kraus and Kawamura in 1928 showed that triphenylmethyl chloride reacts with sodium and potassium in liquid ammonia, but that the potassium compound is more stable than the sodium derivative. A number of compounds similar in structure to triphenylmethyl have since been sho wn to give similar reactions. Rubidium and esesium also form similar derivatives. ... 

D-Berine methyl ester is converted into the IJ-triphenylmethyl derivative which, when heated in the presence of methane sulphonyl chloride, yielded the substituted ethylene-amine (2). Reaction of (2) with hydroxyl-amine and sodium methoxide gives the corresponding hydroxamic acid (3) This product is converted, by the action of hydrochloric acid, into D-a amiso-3-chloro-H-hydroxypropionamide (k), which undergoes cyclization to D-cycloserine (5) when treated with a strongly basic ion exchange resin. 

Yet another type of hydrocarbyl bridging has been established for some solvated triphenylmethyl derivatives of the heavier alkali metals. [NaCPh3(tmeda)] , 64, and [KCPh3(diglyme)] , 66 [57], are supramolecularly associated into zigzag chains by weak intermolecular sodium-carbon contacts. 

Williams and Rastetter also accomplished an elegant synthesis of ( )-hyalodendrin (83) in 1980 [39]. Beginning with the sarcosine anhydride-derived enolic aldehyde 78, silyl protection of the enal enabled alkylation of the glycine center with benzyl bromide and thiolation using LDA and monoclinic sulfur a la Schmidt. After protection of the thiol with methylsulfenyl chloride and deprotection of the silyl ether, the enol was sulfenylated with triphenylmethyl chlorodisulfide to afford bis(disulfide) 82 as a 2 1 mixture of diastereomers favoring the anti isomer. Reduction of the disulfides with sodium borohydride and oxidation with KI3 in pyridine afforded ( )-hyalodendrin (83) in 29 % yield (Scheme 9.4). 

The site of reaction on an unsaturated organometallic molecule is not restricted to the most probable position of the metallic atom or cation or to a position corresponding to any one resonance structure of the anion. This has been discussed in a previous section with reference to the special case of reaction with a proton. Although the multiple reactivity is particularly noticeable in the case of derivatives of carbonyl compounds, it is not entirely lacking even in the case of the derivatives of unsaturated hydrocarbons. Triphenylmethyl sodium reacts with triphenylsilyl chloride to give not only the substance related to hexaphenylethane but also a substance related to Chichi-babin s hydrocarbon.401 It will be recalled that both the triphenyl-carbonium ion and triphenylmethyl radical did the same sort of thing. 

Another differential reaction is copolymerization. An equi-molar mixture of styrene and methyl methacrylate gives copolymers of different composition depending on the initiator. The radical chains started by benzoyl peroxide are 51 % polystyrene, the cationic chains from stannic chloride or boron trifluoride etherate are 100% polystyrene, and the anionic chains from sodium or potassium are more than 99 % polymethyl methacrylate.444 The radicals attack either monomer indiscriminately, the carbanions prefer methyl methacrylate and the carbonium ions prefer styrene. As can be seen from the data of Table XIV, the reactivity of a radical varies considerably with its structure, and it is worth considering whether this variability would be enough to make a radical derived from sodium or potassium give 99 % polymethyl methacrylate.446 If so, the alkali metal intitiated polymerization would not need to be a carbanionic chain reaction. However, the polymer initiated by triphenylmethyl sodium is also about 99% polymethyl methacrylate, whereas tert-butyl peroxide and >-chlorobenzoyl peroxide give 49 to 51 % styrene in the initial polymer.445... 

Essentially covalent compounds such as the lithium alkyls. Derivatives of any alkali metal where charge delocalization can occur over several carbon atoms (e. g. triphenylmethyl-sodium, lithium-benzyl) were also considered to be largely ionic in constitution. 

A 1-Pyrroline V-oxides dimerize readily in alkaline media.335 Different products are obtained on treatment of 2,2-dimethyl-d1-pyrroline V-oxide with sodamide or triphenylmethyl sodium.338 Sodium-potassium alloy in ethylene glycol produces a derivative of 1, r-dihydroxy-2,2 -dipyrrolidyl.337... 

Rubidium triphenylmethyl, RbCPhg, prepared in a similar manner to the lithium compound, is a dark-red powder resembling the sodium and potassium derivatives. It gives a blood-red solution in ether. 

Organolithium compounds, generally phenyl- or butyllithium, can be used, in the same way as(triphenylmethyl)sodium (see page 917), as base for C-alkyla-tion, since in certain cases they react by metal exchange with activated hydrocarbons. For instance, the 2-lithio derivative of resorcinol dimethyl ether is formed in 70% yield on reaction with phenyllithium. The organolithium compounds thus obtained react readily with alkyl halides or sulfates, forming a carbon-carbon bond 326 for example, 2,6-dimethoxytoluene is formed by... 

Dialkyl-substituted / -oxo esters are obtained free from monoalkylated products by acylating the sodio derivatives of, <%-dialkylated acetic esters, the latter being accessible as described above (page 917) from a disubstituted acetic ester and (triphenylmethyl)sodium.431... 

Triphenylmethyl radicals react immediately with several reagents to form triph-enyhnethyl derivatives, for example, with oxygen it forms colorless peroxide, and combines with sodium to form triphenylmethyl sodium, a brick-red soHd. In addition, it can act as a powerful reducing agent, and will reduce the salts of silver, gold, and mercury to the metals (Scheme 4.3). 

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