Doebner-type pyrazolopyridine carboxylic acids in an Ugi four-component reaction

1. Maryna V. Murlykina,
2. Oleksandr V. Kolomiets,
3. Maryna M. Kornet,
4. Yana I. Sakhno,
5. Sergey M. Desenko,
6. Victoriya V. Dyakonenko,
7. Svetlana V. Shishkina,
8. Oleksandr A. Brazhko,
9. Vladimir I. Musatov,
10. Alexander V. Tsygankov,
11. Erik V. Van der Eycken and
12. Valentyn A. Chebanov