1,6-Conjugated Addition of Nitromethane to (E)-2-Styrylchromones: A New Synthesis of Novel 2-Substituted 4-Arylpyrrole Derivatives

The 1,6-conjugate addition of nitromethane to (E)-2-styrylchromones were achieved, in moderate to good yields, by using DBU as organocatalyst. Reduction studies on the 2-(2-aryl-3-nitropropyl) chromone adducts formed surprisingly led to novel 2-substituted 4-arylpyrrole derivatives. These new derivatives are formed from nitro-group reduction, followed by a 1,4-Michael-type addition of the primary amine intermediate to the alpha, beta-unsaturated carbonyl system of the chromone moiety and concomitant heterocyclic ring opening.