Synthesis of 5-substituted 2-pyrrolidinones by coupling of organozinc reagents with cyclic N-acyliminium ions

Abstract

A coupling reaction between cyclic N-acyliminium ions with organozinc reagents is described. The cyclic N-acyliminium ions, generated in situ from N-substituted-5-hydroxy-2-pyrrolidinones by treatment with BF3-etherate or titanium tetrachloride, were trapped by the organozinc reagent, formed by the alkylbromide in the presence of zinc in the same reaction media. The N-substituted 5-allyl-2-pyrrolidinones generated using this method, serves as versatile intermediates for the synthesis of azabicyclic systems with indolizidine and pyrroloazepinolizidine cores.