Stereoselective synthesis of the northern hemisphere of the proposed structure of neaumycin B

The stereoselective synthesis of the northern hemisphere (C₂₀–C₄₁) of the purported structure of the extremely potent anticancer natural product neaumycin B has been accomplished. Twelve out of nineteen asymmetry centers have been installed chemically. The key highlights of this synthesis include the Krische iridium catalyzed anti-diastereoselective carbonyl crotylation, the Crimmins aldol reaction, HWE olefination, CBS reduction, vanadium promoted stereoselective epoxidation, Evans methylation and spiroketalization.