Abstract In this paper, we report the results of heterocyclizations in the pyrido [2, 3-b] pyrazine series to give the pyrido [2, 3-e] or [3, 2-e] pyrrolo [1, 2-a] pyrazine. The Clauson- Kaas reaction on 2, 3-diaminopyridine is investigated; regioselectivity on the 3-amino group is shown by 1 H-and 13 C-nmr. Synthesis and reactivity of the original pyrazino [2, 3-g] indolizine series is also reported.
![6-methylpyrido[2,3-b]pyrazine Structure](https://image.chemsrc.com/caspic/071/155629-96-2.png)