Thermal and photochemical annulation of vinyl azides to 2-aminoimidazoles.

2-Aminoimidazoles represent useful synthons for incorporation into medicinal compounds. They provide hydrogen bonding loci, water solubilizing properties and convenient handles for further synthetic elaboration. The rapid and facile generation of diverse 2-aminoimidazoles via tandem addition cyclization reaction of vinyl azides and cyanamide has been investigated. These reactions proceeded through either thermal or photochemical activation of vinyl azides and demonstrated wide substrate scope. In the photochemical reaction, blue light (456 nm) alone triggered photolysis of the azide without the addition of a photocatalyst. Possible reaction mechanisms in the context of substrate reactivity are discussed.