L-Proline catalyzed condensation of salicylaldehydes with ethyl nitroacetate: an efficient access to 3-nitrocoumarins

摘要

l-Proline catalyzed condensation of salicylaldehydes and ethyl nitroacetate afforded 3-nitrocoumarins in good to high yields under mild conditions. This organocatalyzed process offers a much improved yield of 3-nitrocoumarins and well tolerates both electron-donating and electron-withdrawing substituents on the phenyl ring.