Solid-phase synthesis of tetramic acids

Upon treatment with base, N-acylated α-amino acids loaded on Wang resin undergo cyclative Claisen-type condensation to release the tetramic acid in high yield and purity. The use of tetrabutylammonium hydroxide as base simplifies product purification, as it can be scavenged by acidic Amberlyst A-15 ion exchange resin. The diversity of the tetramic acids can be further increased by reductive alkylation of the starting amino acid.