Abstract The first total synthesis of geralcin A (2), a naturally occurring α, β-unsaturated γ- lactonohydrazide produced by Streptomyces sp. LMA-545, was achieved according to the hypothetical biosynthesis we have previously published. MH-031 (1), the plausible natural precursor isolated together with geralcin A, was synthesized in 6 steps and in a 25% overall yield. Condensation of glycolic acid with key intermediate Boc-hexylhydrazine afforded ...