Phase Separation Macrocyclization in a Complex Pharmaceutical Setting: Application toward the Synthesis of Vaniprevir.

A phase separation/continuous flow strategy employing an oxidative Glaser-Hay coupling of alkynes has been applied toward the synthesis of the macrocyclic core of complex pharmaceutical vaniprevir. The phase separation/continuous flow strategy afforded similar yields at 100-500 times the concentration and at shorter reaction times than common slow addition/high dilution techniques. In addition, dendritic PEG cosolvents were employed in the phase separation strategy for the first time and shown to allow productive macrocyclization at concentrations up to 200 mM.