HFIP-mediated cascade aminomethylation and intramolecular cyclization of allenamides with ,-acetals to access tetrahydro-β-carboline derivatives.

The construction of complex molecules under metal-free conditions multiple bond-forming steps in a cascade manner is highly desirable. Herein, we have developed an HFIP-alone promoted aminomethylation and intramolecular cyclization of allenamides, providing biologically relevant tetrahydro-β-carboline derivatives embedded with an allylic amine functionality. The metal-free protocol provided the desired tetrahydro-β-carboline derivatives under mild conditions.

Facile access to -substituted piperazin-2-ones and mianserin derivative enabled by chemoselective carbene insertion and cyclization cascade.

The chemoselective N-H insertion of unsymmetrical diamines into carbene is a longstanding challenge. A simple copper-catalyzed strategy for synthesizing -substituted piperazinones is described, employing easily accessible diazo compounds and 1,2-diamines. The reaction proceeded chemo-selective carbene insertion at the comparatively less nucleophilic amine, followed by instantaneous cyclization.