Grignard results

The unstable dinuclear complex [(7r-Cp)2Pr Ti]2 has been obtained from the reaction of [(7 -Cp)2TiCl] with Pr MgCl in ether under a nitrogen atmosphere at 193—173 K. An excess of the Grignard resulted in a slow transformation of this blue complex into a black derivative which quantitatively evolved hydrazine when treated with HCl. ... 

These results and of course some of the Grignard results where retention mechanisms in phosphonates are preponderant show that caution must be taken when even a foundation stone of modern phosphorus stereochemistry is being considered. 

The yields" of the Grignard reagents are usually 90% or higher too fast an addition of RBr, however, may result in the formation of substantial amounts of R-R, especially in the case of bromobenzene. 

The phenylation of styrene with phenyl Grignard reagents as a hard carbon nucleophile proceeds in 75% yield in the presence of PdCl2, LiCl, and K2CO3 at room temperature to give stilbene (207). Selection of the solvent is crucial and the best results are obtained in MeCN. The reaction can be made catalytic by the use of CuCl2[197]. Methyllithium reacts with styrene in the presence of Pd(acac)2 or Pd(OAc)2 to give /3-methylstyrene (208) in 90% yield[198]. 

Using only the phenyhnagnesium chloride without the MnCI catalyst results ia a mixture of products. This mixture iacludes the alcohol(s) resulting from the diaddition of the Grignard reagent to the carbonyl groups. Other catalysts, such as Fe(III) and Ni(II), have also been used to achieve similar results... 

Cesium forms simple alkyl and aryl compounds that are similar to those of the other alkah metals (6). They are colorless, sohd, amorphous, nonvolatile, and insoluble, except by decomposition, in most solvents except diethylzinc. As a result of exceptional reactivity, cesium aryls should be effective in alkylations wherever other alkaline alkyls or Grignard reagents have failed (see Grignard reactions). Cesium reacts with hydrocarbons in which the activity of a C—H link is increased by attachment to the carbon atom of doubly linked or aromatic radicals. A brown, sohd addition product is formed when cesium reacts with ethylene, and a very reactive dark red powder, triphenylmethylcesium [76-83-5] (C H )2CCs, is formed by the reaction of cesium amalgam and a solution of triphenylmethyl chloride in anhydrous ether. 

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