Cesium carbonate → tert-Butyl 6-nitro-3',6'-dihydro-[3,4'-bipyridine]-1'(2'H)-carboxylate

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Reaction Steps

A solution of 4-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-3,6-dihydro-2H-pyridine-1-carboxylic acid tert-butyl ester (5.38 g, 17.40 mmol), 5-bromo-2-nitro-pyridine (3.52 g, 17.40 mmol), Cs2CO3 (11.34 g, 34.8 mmol), and Pd(PPh3)2Cl2 (1.27 g, 1.74 mmol) in dioxane (50 mL) was stirred at 85° C. under N2 atmosphere overnight. TLC showed a complete reaction. The solution was poured onto water and extracted with ethyl acetate. The combined organic layers were washed with brine, dried over Na2SO4, and concentrated. Purification by column chromatography on silica gel (petroleum ether:ethyl acetate, 2:1 eluent) afforded the desired product as yellow solid (3.37 g, 64%). 1H NMR (300 MHz, CDCl3): δ 8.63 (d, J=2.4 Hz, 1H), 8.20 (d, J=8.4 Hz, 1H), 7.93 (dd, J=8.4, 2.4 Hz, 1H), 6.31 (s, 1H), 4.17-4.14 (m, 2H), 3.68 (t, J=5.7 Hz, 1H), 2.57-2.54 (m, 2H), 1.49 (s, 9H).

Provenance & Evidence