Scalable Synthesis of the Desoxy-biphenomycin B Core

We describe the evolution of a kilogram-scale synthesis of the protected cyclic tripeptide desoxy-biphenomycin B, based on an early discovery route. The retrosynthetic concept included a macrolactamization strategy to build the core ring system of biphenomycin B in combination with a double catalytic asymmetric hydrogenation protocol for the construction of the ansa-tripeptide precursor. Eventually, the kilogram process comprised a 16-step sequence with an overall yield for the longest linear sequence of 19.5%.