Synthesis of polycyclic alkaloid-type compounds by an N -acyliminium Pictet-Spengler/diels-alder sequence

Abstract

A range of structurally diverse penta- and hexacyclic alkaloid-type compounds have been prepared in a two-step procedure from readily available starting materials. A flexible N-acyliminium Pictet-Spengler reaction employing electron-rich -arylethyl-amines, cinnamaldehyde derivatives, and alkynoyl chlorides sets the stage for an intramolecular Diels-Alder cycloaddition. The complex and diverse polycyclic alkaloid-like compounds are easily obtained in reasonable to excellent yield in a reliable and efficient reaction sequence. © Georg Thieme Verlag Stuttgart New York.