Methyl 5-((2S,4R)-1-acetyl-4-((5-cyanopyridin-2-yl)amino)-2-methyl-1,2,3,4-tetrahydroquinolin-6-yl)picolinate (for a preparation see Intermediate 33)(2.94 g, 6.66 mmol) was dissolved in anhydrous 1,4-dioxane (20 ml). Water (20.0 ml) was added followed by lithium hydroxide (0.319 g, 13.32 mmol) and reaction mixture stirred at r.t. After 1 h, the 1,4-dioxane was removed in vacuo and aqueous residue was treated with acetic acid (1.144 ml, 19.98 mmol). The resulting orange precipitate was stirred for 20 min, isolated by filtration, washed with water and dried under vacuum overnight to give 5-((2S,4R)-1-acetyl-4-((5-cyanopyridin-2-yl)amino)-2-methyl-1,2,3,4-tetrahydroquinolin-6-yl)picolinic acid (2.16 g, 4.55 mmol, 68.3% yield) as a brown solid. LCMS (Formate, 2 min), Rt=0.68 min, MH+=428.
