Electron transfer reactions from alkali metal surfaces to (±) and (S)-(−)-1,3-dimethoxy-1,1-diphenylbutane. Studies on 1,3-elimination

The 1,3-elimination of methoxide by carbanions generated from the reaction of (±)-1,3-dimethoxy-1,1-diphenylbutane with the alkali metals, lithium, sodium, and potassium, in various solvents was studied to determine the significance of cation–methoxyl coordination due to decreasing charge/radius ratio of the cations and also the cation complexing ability of the solvent. The stereochemistry of cyclization in the reaction of (S)-(−)-1,3-dimethoxy-1,1-diphenylbutane with lithium metal in tetrahydrofuran and with sodium metal in methylcyclohexane to yield 1-methyl-2,2-diphenylcyclopropane was determined. The reaction proceeded by an intramolecular S N 2-type displacement to yield optically pure product of inverted configuration.