Diversely Substituted Imidazo[1,2‐<i>a</i>]pyrazine‐8‐oxo‐3‐carbaldehydes: An Iodine‐Mediated Cyclization/Oxidation Approach

Abstract

Abstract A mild and efficient iodine‐mediated intramolecular heteroannulation approach for the construction of the imidazo[1,2‐ a ]pyrazinone core has been developed. Under ambient conditions, this metal‐free protocol allows easy access to densely functionalized imidazo[1,2‐ a ]pyrazinone‐3‐carbaldehydes or (aminomethyl)imidazo[1,2‐ a ]pyrazinones from substrates containing terminal alkynes by cyclization and subsequent oxidation or amination. Further diversification may be introduced by using substrates containing an internal alkyne and/or Suzuki coupling after cyclization to generate polysubstituted (dihydro)imidazo[1,2‐ a ]pyrazinones.