On the stereoselectivity of the α-alkylation of β-hydroxy esters. Enantioselective synthesis of 4,4- and 6,6-disubstituted cyclohex-2-en-1-ones.

Stereoselective α-alkylation of the optically active 6-hydroxyester $\text{1}$ gives rise to $\text{2}$, which was converted to the 1,5-diketone $\text{4}$. Regioselective aldolcondensation of the latter furnished (S)-$\text{5}$ and (S)-$\text{6}$ respectively, each with an e.e. of 86%.