[2+2+2] Cycloadditions of Alkynylynamides – A Total Synthesis of Perlolyrine and the First Total Synthesis of “Isoperlolyrine”

The total syntheses of the carboline alkaloids perlolyrine and “isoperlolyrine” are reported. Key‐steps of the syntheses are Negishi coupling reactions on alkynylynamides and their metal‐catalyzed [2+2+2] cycloadditions with nitriles to form the β‐ and γ‐carboline cores. The choice of the catalyst strongly affects the β/γ ratio. Spectroscopic features of the γ‐isomer are distinctly different from those of the naturally occurring isoperlolyrine.