From Simple Cyclic 1,3-Ketoamides to Complex Spirolactams by Supported Heterogeneous Organocatalysis with PS-BEMP

Abstract : The reaction between cyclic 1,3-ketoamides and Michael acceptors in the presence of a catalytic amount of a polymer-supported organobase PS-BEMP has been developed for a direct access to spirocyclic 1,3-ketolactams through a domino Michael addition/hemiacetalization sequence. The products could be isolated in high chemical yields and purities after simple filtration, and the catalyst could be re-used without any re-activation. These spirolactams, containing a hemiaminal moiety, may be viewed as precursors of N-acyliminium intermediates upon Lewis acid activation, which allowed various subsequent functionalizations leading to original polycyclic lactams.