Catalytic Enantioselective Alkylation of Substituted Dioxanone Enol Ethers:Ready Access to C(alpha)-Tetrasubstituted Hydroxyketones,Acids,and Esters

摘要

The catalytic enantioselective formation of tetrasubstituted alpha-alkoxycarbonyl compounds is an ongoing challenge to synthetic chemists.Fully substituted alpha-hydroxyesters and acids comprise essential components of,and building blocks for,many bioactive natural products(see Figure 1).These include quinic acid(1),cytotoxic leiodolide A(2),and the anticancer agents in the harringtonine series(3a-f),whose activities depend dramatically on the presence and composition of an alpha-hydroxyester side-chain.