Yield: 76%

Reaction Conditions:

with N-Bromosuccinimide;sodium hydrogencarbonate in N,N-dimethyl-formamide at 20; for 4 h;

Steps:

22.c
N-Bromosuccinimide (3.06 g, 17.22 mmol) and sodium hydrogen carbonate (4.34 g, 51.66 mmol) were added to a solution of pyrazolo[1 ,5-a]pyridine-3-carboxylic acid (Preparation 22b, 2.81 g, 17.22 mmol) in A/.A/'-dimethylformamide (40 mL) and the resulting mixture was stirred at room temperature for 4h before being poured over 100 mL of water. The resulting suspension was extracted twice with ethyl acetate and the combined organic layers were dried over magnesium sulphate, filtered and the solvent was evaporated. The crude product was purified by flash chromatography (8:2 hexane/ethyl acetate) to yield the title compound (2.58 g, 76%).LRMS (m/z): 197 (M+1)⁺.¹H-NMR δ (250 MHz, CDCI₃): 6.8 (t, 1 H), 7.2 (t, 1 H), 7.5 (d, 1 H), 7.9 (s, 1 H), 8.4 (d, 1 H).

References:

ALMIRALL, S.A.;BACH TA?A, Jordi;PAGES SANTACANA, Lluis, Miquel;TALTAVULL MOLL, Joan;EASTWOOD, Paul, Robert;GONZALEZ RODRIGUES, Jacob;GIULIO MATASSA, Victor WO2011/101161, 2011, A1 Location in patent:Page/Page column 99