Total Synthesis of the Biphenyl Alkaloid (−)‐Lythranidine

A sequence comprising a ring‐closing alkyne metathesis of a propargyl alcohol derivative, followed by a ruthenium‐catalyzed redox isomerization of the derived cycloalkyne and a transannular aza‐Michael addition allowed the formation of the distinguishing piperidine‐metacyclophane framework of the Lythraceum alkaloid lythanidine in a few high‐yielding steps. This application attests to the excellent functional‐group tolerance of a molybdenum alkylidyne complex endowed with triphenylsilanolate ligands, which enabled the macrocyclization even in the presence of protic functionalities, and thus illustrates the power of contemporary catalytic acetylene chemistry for target‐oriented synthesis.