Total Synthesis of the Reported Structure of Neaumycin B

The stereoselective total synthesis of structure 1 assigned to the macrolide natural product neaumycin B is reported in a 2.3% overall yield on 90 mg scale. The synthesis features a gram-scale nickel-catalyzed reductive cross-coupling/spiroketalization tactic to construct the spiroketal core of neaumycin B. The stereostructures of the C3–C6, C8–C14, and C20–C41 segments of synthetic neaumycin B were unambiguously verified by X-ray crystallography.