The structure of reductiline, a metabolite of a variant of Streptomyces orientalis, was elucidated as (1) based on chemical and spectroscopic evidence. Transformation of an antitumor antibiotic reductiomycin (2) into reductiline (1) was carried out. Synthesis of reductiline (1) was achieved starting from β-cyanopropionaldehyde dimethylacetal.