Entry to nitrogen-containing heterocycles by base-promoted heterocyclization on allenylamides of L-a-aminoacids

Allenylamides of Boc-protected α-aminoacids easily gave in basic medium heterocyclic products arising from attack of the NH group on the inside C–C double bond of the 1,2-diene moiety, namely imidazolidinones, pyrazinones, and a pyrrole compound. The microwave-assisted heterocyclization occurred cleanly at C-β of the allenyl group with formation of pyrazin-2-ones having an endo- or exocyclic double bond.