Synthesis of the Entomopathogenic Fungus Metabolites Militarinone C and Fumosorinone A

Militarinone C and fumosorinone A, 3-oligoenoyltetramic acids produced by insect pathogenic fungi, were synthesized for the first time. The pyrrolidine-2,4-dione ring was closed through a late-stage Dieckmann condensation of N-(β-ketoacyl) derivatives of tyrosine, obtained by its acylation with either thioesters or Meldrum’s acid derivatives bearing the all-trans-polyene side chain. The latter was built up from (S)-citronellol via an Evans methylation and Wittig or HWE olefinations.