A Microwave‐Assisted One‐Pot Three‐Step Metal‐Free [4+2] Annulation for the Sustainable Synthesis of Highly Substituted 1,2,4‐Triazines

Herein we report the first microwave-assisted one-pot three-step metal-free [4+2] procedure for the synthesis of 5,6-substituted-3-hydrazinyl-1,2,4-triazines directly from commercially available aromatic and heteroaromatic ketones. The 3-hydrazinyl-1,2,4-triazine can be isolated or further elaborated, after a simple work-up, by direct condensation with different aldehydes or ketones to provide highly functionalized hydrazone-derivatives. This protocol represents a rapid, efficient, and sustainable approach for the development of new highly functionalized 1,2,4-triazine derivatives with potential biological interest.Herein we report the first microwave-assisted one-pot three-step metal-free [4+2] procedure for the synthesis of 5,6-substituted-3-hydrazinyl-1,2,4-triazines directly from commercially available aromatic and heteroaromatic ketones. Based on literature, a plausible mechanism is postulated. The 3-hydrazinyl-1,2,4-triazine can be isolated or further elaborated to provide highly functionalized hydrazone-derivatives. image