Total Synthesis of Tyrosine‐Derived Tetramic Acid Pigments from a Slime Mould

Abstract

Abstract A method for the total synthesis of naturally occurring 3‐enoyltetramic acids derived from L ‐tyrosine is described, allowing for three chemical transformations to occur in one pot by using a multicomponent mixture. The sequence involves (1) a base‐promoted Lacey–Dieckmann condensation, (2) a Michaelis–Becker reaction, and (3) a Wittig–Horner–Emmons reaction between the resulting 3‐phosphonoacetyltetramic acid and an appropriate aldehyde. This sequence of reactions was applied to the synthesis of polyenic pigments obtained from the slime mould Leocarpus fragilis starting from readily available precursors. A series of structurally related compounds was also synthesized and their antibiotic significance was evaluated to elucidate their role in nature.