| Abstract: | Organometallic compounds of the alkali metals undergo concerted 1,n] sigmatropic migration of aryl, vinyl, carbonyl, alkoxycarbonyl, silyl, germyl, and related groups. Sigmatropic migration of alkyl, benzyl, and hydrogen occur only under special circumstances and then may occur by an alternate fragmentation-recombination pathway. Allyl groups may migrate by the latter process or by a concerted 2,3] sigmatropic reaction. These molecular rearrangements are discussed from the viewpoint of simple molecular orbital theory. By suitable choice of the alkali metal, temperature, ligands of the alkali cation and/or the solvent, considerable control may be exercised over the rate of rearrangement, the relative migratory aptitude of groups, and the mechanistic pathway. |
