Sodium Carbonate → methyl 3-[bis(tert-butoxycarbonyl)amino]-6-(1-tert-butoxycarbonyl-3,6-dihydro-2H-pyridin-4-yl)pyrazine-2-carboxylate

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Reaction Steps

A suspension of tert-butyl 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-3,6-dihydro-2H-pyridine-1-carboxylate (858 mg, 2.8 mmol), 4-ditert-butylphosphanyl-N,N-dimethyl-aniline; dichloropalladium (164 mg, 0.23 mmol), methyl 3-[bis(tert-butoxycarbonyl)amino]-6-bromo-pyrazine-2-carboxylate (1.0 g, 2.3 mmol), and Na2CO3 (490 mg, 4.6 mmol) under an atmosphere of nitrogen in toluene (15 mL) and water (2 mL) was heated to 95° C. for 2 h. The reaction mixture was diluted with ethyl acetate, washed with 1N HCl, 50% saturated sodium bicarbonate solution, and brine. The organic layer was dried over anhydrous Na2SO4, filtered, and concentrated. The crude product was purified via silica gel column chromatography using 10-50% ethyl acetate/hexane to provide methyl 3-[bis(tert-butoxycarbonyl)amino]-6-(1-tert-butoxycarbonyl-3,6-dihydro-2H-pyridin-4-yl)pyrazine-2-carboxylate (1.2 g, 97%) as a amber oil. 1H NMR (400 MHz, DMSO-d6) δ 9.03 (s, 1H), 6.97 (s, 1H), 4.12 (s, 2H), 3.89 (s, 3H), 3.57 (t, J=5.2 Hz, 2H), 2.61 (s, 2H), 1.43 (s, 9H), 1.34 (s, 18H). LC/MS m/z 535.5 [M+H]+.

Provenance & Evidence