[4 + 2] Annulation Reaction of <i>In Situ</i> Generated Azoalkenes with Azlactones: Access to 4,5-Dihydropyridazin-3(2<i>H</i>)-Ones
Wei‐Cheng Yuan, Bao-Xue Quan, Jian‐Qiang Zhao, Yong You, Zhen‐Hua Wang, Ming‐Qiang Zhou
Abstract
An unprecedented [4 + 2] annulation reaction between in situ formed azoalkenes and azlactones has been developed. This reaction provides a facile access to an array of 4,5-dihydropyridazin-3(2 H )-one derivatives, which are very promising in medicinal applications as potential biologically active candidates. Notably, these dihydropyridazinones could also be synthesized via a one-pot reaction protocol by using the in situ formed azlactones from N -acyl amino acids and in situ generated azoalkenes from α-halogeno hydrazones. The potential applications of the methodology were also demonstrated by gram-scale experiments and the versatile conversions of the products into other nitrogen-containing compounds.