Alkynyl Phenyl Selenides as Intermediates in the Metal‐Free Cyclisation of <i>N</i>‐Tosyl Homopropargyl Amides to γ‐Lactams

Abstract In this work, we present an efficient Brønsted acid‐catalysed intramolecular hydroamination reaction of homopropargyl N‐tosyl amides to produce synthetically useful substituted γ‐lactams through the corresponding alkynyl phenyl selenide intermediates. Our focus on optimising the cyclisation protocol under flow conditions has led to a significant enhancement in efficiency, thereby reducing the time and resources required for the process. DFT calculations of the reaction mechanism for the catalytic transformation of a model alkynyl phenyl selenide were also conducted.