Perchloric Acid → (S)-methyl 2-(2-bromo-7-(4,4-dimethylpiperidin-1-yl)-5-methylpyrazolo[1,5-a]pyrimidin-6-yl)-2-(tert-butoxy)acetate

Beteiligte Stoffe

Reaktionsschritte

To a solution of (S)-methyl 2-(2-bromo-7-(4,4-dimethylpiperidin-1-yl)-5-methylpyrazolo[1,5-a]pyrimidin-6-yl)-2-hydroxyacetate (5.68 g, 13.81 mmol, 1 equiv) in DCM (92 mL) and t-butyl acetate (184 mL) was added 70% perchloric acid (3.3 mL, 55.2 mmol, 4 equiv). The reaction turned pale yellow. After 3 h, the reaction was added very cautiously to a saturated aqueous solution of NaHCO3 and extracted with CHCl3 (×3). Combined organic extracts dried over Na2SO4 and concentrated in vacuo. The crude product was purified by silica gel flash chromatography (0-70% EtOAc/hexane) to provide (S)-methyl 2-(2-bromo-7-(4,4-dimethylpiperidin-1-yl)-5-methylpyrazolo[1,5-a]pyrimidin-6-yl)-2-(tert-butoxy)acetate as a pale yellow solid (2.8 g, 43%) and recovered starting material (3.0 g, 53%). 1H NMR (400 MHz, CDCl3) δ 6.54 (s, 1H), 5.92 (s, 1H), 3.74 (s, 3H), 2.59 (s, 3H), 1.58 (s, 8H), 1.24 (s, 9H), 1.11 (s, 6H); LCMS (ESI, M+1):467.3.

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