Asymmetric Aldol Reaction Using Solid-Supported Proline Catalysts

Significance

PS-PEG resin-supported proline-terminated peptides 1a-j were readily prepared from Pro, Ala, Ser, Thr, Cys, Phe, Trp, Tyr and commercially available TentaGel amino resin by the standard Fmoc-based methodology using HBTU, HOBt and DIPEA as coupling reagents. Asymmetric aldol reaction of 4-nitrobenzaldehyde (2) with acetone was carried out in the presence of 1a-j to give ( S )-4-hydroxy-4-(4-nitrophenyl)butan-2-one (3) of up to 82% ee via the aldol transition state 4.