Synthesis of Five-Membered Cyclic Guanidines via Cascade [3 + 2] Cycloaddition of α-Haloamides with Organo-cyanamides.

The convenient preparation of N2-unprotected five-membered cyclic guanidines was achieved through a cascade [3 + 2] cycloaddition between organo-cyanamides and α-haloamides under mild conditions in good to excellent yields (up to 99%). The corresponding cyclic guanidines could be easily transformed into hydantoins via hydrolysis.

Synthesis of Sulfamate-Fused 2-Aminopyrroles via an Isocyanide-Based Three Component [1+2+2] Annulation.

An efficient preparation of sulfamate-fused 2-aminopyrroles was achieved through an isocyanide-based three-component [1+2+2] annulation of isocyanides, dialkyl acetylenedicarboxylates, and sulfamate-derived cyclic imines in good to excellent yields (up to 99 %). This reaction proceeds smoothly without any activation or modification of substances under neutral and metal-free conditions. The reaction could also be conveniently performed on a gram scale.