Abstract Total synthesis tetronasin (1), a tetronic acid polyether ionophore antibiotic, is reported in which the γ-unsubstituted α-acyltetronic acid structure is constructed by cyclization of a β-keto ester derivative 18 derived from tricyclic aldehyde intermediate 17 by reaction with methyl (diazoacetoxy) acetate in the presence of zirconium tetrachloride.
