Configuration lithium compounds, organo

Hoffmann and coworkers proposed an excellent method for evaluating the configurational stability of the lithium carbanion within the time scale of the rate of the reaction with an electrophile (Hoffmann test) [12]. The Hoffmann test is composed of two experiments. In the first experiment, a racemic organo-lithium compound is reacted with a racemic aldehyde such as 2-(Nd -diben-zylamino)-3-phenylpropanal,the relative rate of formation of the diastereomeric products (k55 kjjj) being estimated by an antUsyn ratio of the products (Fig. 5). 

Subsequent work by D. Braun and collaborators dealt with the effect of solvent polarity and countercation on the tacticity of poly(methyl methacrylate) (PMMA) initiated with various organo alkali metal compounds. By using proton NMR analysis they concluded that polar solvents and alkyl lithium initiators favored syndiotactic configurate on( ) while non-polar solvents favored isotactic piacement( )." ... 

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