An efficient synthetic route to highly substituted pyrrolidone derivatives has been
developed from an easily available alkynyl carboxamide and 4-methylbenzenesulfonic
acid (PTSA). In the reaction, PTSA is not only used as acid catalyst but also as a
reactant to provide a source for OTs group. A mechanism is proposed to involve the
protonation of the alcohol substrate/cyclopropylcarbinol-homoallylic rearrangement/intramolecular
N-nucleophilic cyclization reactions.
Keywords
pyrrolidones - alkynyl carboxamides - PTSA - intramolecular cyclization - ring opening