Oxidative Aromatization of 1,3,5-trisubstituted 2-pyrazolines Using Oxalic Acid/Sodium Nitrite System

<p>Oxidative aromatization of 1,3,5-trisubstituted 2-pyrazolines by <i>in-situ</i> generation of NO⁺ from oxalic acid/sodium nitrite system has been described. The main advantages of this procedure are the use of an inexpensive and readily available catalyst, facile work-up, and improved yields in aqueous ethanol.</p