Organomagnesiums lithium metal

Whereas alkylphosphonic diesters react readily with lithium or organomagnesium reagents with the formation of the metallated phosphonate carbanions, the reactions between such esters and the metals themselves result, by contrast, in dealkylation of the ester groups involving both C-0 and P-0 cleavage traces of unsaturated hydrocarbons, even including alkynes and aromatics, are thought to be formed by radical-induced reactions. 

The use of organomagnesium reagents as bases leads to complexation of the nitrile imines (e.g., 141), which has been found to have a strong effect in promoting syn selectivity in reactions with methyl 2-(l-hydroxyalkyl)acrylates via coordination of the metal atom with the alcoholic oxygen (e.g., leading to the formation of 142). Lithium complexation had little effect (78). 

Understanding of chemical bonding is needed to understand which bond types are possible and to draw relations to the physical behavior of organomagnesium compounds. Comparison with other main group metals, especially lithium, is of interest. 

Organo -Ca, -Sr and -Ba derivatives are prepared from the metals. With Be, however, the compounds are produced from anhydr BeCl2 and organomagnesium-halide reagents or lithium alkyls. In principle, RBe derivatives can also be formed from Be metal. Thus, a Be mirror disappears by the effect of alkyl radicals, but such reactions cannot be used in practice. Beryllium dialkyls also can be prepared from olefins and Hj with the metal in the presence of small amounts of Br2 or I2, and by the electrolysis of M[A1R3R ] complexes (M = Na, K R = alkyl R = alkyl, alkoxy) using anodes of pure Be. However, laboratory application is limited owing to the lack of detailed information and the need for expensive apparatus. 

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