Mixed main-group metal alkyls and alkoxides in synthesis and catalysis

The organic derivatives of sodium and potassium are generally insoluble in hydrocarbons while their instability in ethers, for example, precludes long -term storage of solutions and thus restricts their wider application. Addi tion of magnesium 2-ethoxyethoxide produces hydrocarbon-soluble reagents wi th reactivity comparable with that of the simple organometallics. The organ oalkali-metal reagents in the presence of magnesium 2-ethoxyethoxide in tet rahydrofuran become almost inert towards cleavage of the solvent while reta ining organoalkali-metal-like metallation characteristics. The metallating ability of organolithium reagents can be modified by addition of suitable m etal alkoxides, Mixed alkali-metal dialkylaminoalkoxides combine the activa ting properties of an alkoxide with those of a tertiary amine, while magnes ium 2-ethoxyethoxide greatly reduces the metallating ability and unwanted s ide reactions can be avoided. Certain allylic or benzylic organolithium rea gents, in the presence of mixed lithium potassium dialkylaminoalkoxides, an d in some cases also of magnesium 2-ethoxyethoxide, add either stoichiometr ically or catalytically to ethylene to produce mono- or poly-ethylated deri vatives. In this way substantial quantities of interesting sterically deman ding aromatic derivatives have been produced in good yield. Copyright (C) 2 000 John Wiley & Sons, Ltd.