Abstract
A highly efficient KOtBu‐mediated aza‐Michael addition of aromatic amines and/or N‐phenylurea derivatives to 3‐nitro‐2‐phenyl‐2H‐chromenes and sequential aerobic dehydrogenation is reported. This method provides a novel protocol for C–N bond formation in 3‐nitro‐2‐phenyl‐2H‐chromenes under cost‐effective and operationally convenient conditions. A wide range of 4‐(phenylamino)‐3‐nitro‐2‐phenyl‐2H‐chromenes have been synthesized in good‐to‐high yields (68–86 %) at 35–40 °C within 5–10 minutes.
An efficient KOtBu‐mediated aza‐Michael addition of aromatic amines and/or N‐phenylurea derivatives to 3‐nitro‐2‐phenyl‐2H‐chromenes followed by aerobic dehydrogenation is reported. A wide range of 4‐(phenylamino)‐3‐nitro‐2‐phenyl‐2H‐chromene derivatives were synthesized in good‐to‐high yields (68–86 %) at 35–40 °C within 5–10 minutes under cost‐effective and operationally convenient conditions.