(Alkali metal)decarboxylation reaction: Lone pair participation and design of diastereoselective enolate formation

Recently, we demonstrated that, contrary to the explanation in most textbooks on organic chemistry, the mechanism of the decarboxylation reaction can be more appropriately explained by the orbital theory, since the most electrondonating bond orbital, i.e., the highest occupied bond orbital, in a carbonyl group should be the lone pair on the oxygen, not the .pi.-bond orbital of the C=O bond. Thus, the electron moves from the lone pair to the .sigma.*-orbital of the OH bond, not from the .pi.-orbital of the carbonyl group. With this insight, we succeeded in developing the boradecarboxylation reaction. In our initial screening, the alkali metals were not so promising since they decomposed in TSs. However, the calculations were performed without considering solvation in the gas phase. We supposed that this was influenced by the strongly ionic character of the alkali metal ions. We reconsidered the calculations including those involv-ing the solvent molecules, dimethyl ether (DME) and THF.