Imidazo pyridazinones

The rhodium-catalyzed synthesis of 2-picolylamines and imidazo[l,5-a]pyridines from pyridotriazoles has been achieved (Scheme 3.16) [16], For the preparation of 2-picolylamines (Example 3.4), the reaction was operationally simple and consisted of stirring a dinuclear rhodium catalyst with the two reagents at 120 °C. This approach tolerated a broad spectrum of preexisting functional groups, and even 3(2-/0-pyridazinone was successfully used. For the preparation of the imidazo[l,5-fl]pyridines, a two-stage approach was used for the preparation of the heterocycles that included an initial N-H insertion followed by cyclization. 

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