Asymmetric Aldol Synthesis: Choice of Organocatalyst and Conditions

This is the first report of a successful asymmetric aldol reaction of acetone and 4-nitrobenzaldehyde catalyzed by only 0.01 mol % of proline tetrazole (5-pyrrolidin-2-yltetrazole). Amazingly, 3 mol % of water as an additive has significantly improved the efficiency of the aldol reaction in terms of yield and enantioselectivity, up to a 0.1-mol-scale production (up to 99 % isolated yield, 84 % ee).