REGIOSELECTIVE PROTONATION OF ALLYLLITHIUM COMPOUNDS

By varying the general acid, the regioselectivity of the protonation o f (triphenylsilyl)allyllithium (1) in diethyl ether in the presence of HMPT can be changed from 9:1 to 1:9 at room temperature. When other a protic solvents are used, the nature of the lithium salt changes, and the selectivity decreases. The regioselectivity of the protonation of the dithio-stabilized allyllithium 4 by water is highly dependent on t he age of the allyllithium solution with alpha/gamma ratios varying fr om 2.7:1 to 1:3.5.