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.
Key words
supported organobase - Michael addition - spirolactam - heterogeneous organocatalysis
-
N-acyliminium intermediate