N-Boc-4-aminopyrazole-5-carbaldehydes react with methyl 3,3-dimethoxypropanoate or β-keto esters in acetic acid under reflux to form methyl(ethyl) pyrazolo[4,3-b]pyridine-6-carboxylates, which were converted to the corresponding tert-butyl carboxylates via intermediate carboxylic acids. Their subsequent hydrogenation on a 10% Pd/C catalyst at 100°C and 25 atm afforded tert-butyl 4,5,6,7-tetrahydropyrazolo[4,3-b]pyridine-6-carboxylates.

中文翻译：

---

甲基(乙基)吡唑并[4,3-b]吡啶-6-羧酸酯的合成及其向4,5,6,7-四氢吡唑并-[4,3-b]吡啶-6-羧酸叔丁酯的转化

N -Boc-4-氨基吡唑-5-甲醛与3,3-二甲氧基丙酸甲酯或β-酮酯在乙酸中回流反应生成吡唑并[4,3 - b ]吡啶-6-羧酸甲酯（通过中间体羧酸转化为相应的羧酸叔丁酯。它们随后在 10% Pd/C 催化剂上在 100°C 和 25 个大气压下氢化，得到4,5,6,7-四氢吡唑并[4,3 - b ]吡啶-6-羧酸叔丁酯。