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With 1,1'-bis-(diphenylphosphino)ferrocene; tris-(dibenzylideneacetone)dipalladium(0); caesium carbonate; In toluene; at 80℃; for 3.0h;Inert atmosphere; |
tert-Butyl 6-{1-[(benzyloxy)carbonyl]hydrazino}pyridine-2-carboxylate tert-Butyl 6-chloropyridine-2-carboxylate (91.1 g, 0.43 mol), benzyl hydrazinecarboxylate (70.9 g, 0.43 mol), caesium carbonate (174 g, 0.53 mol) and 1,1'-bis(diphenylphosphino)ferrocene (17.1 g, 32.0 mmol) were suspended in toluene (1.00 l) under argon. Bis(dibenzylideneacetone)palladium(0) (9.76 g, 10.7 mmol) was added, and the reaction mixture was stirred at 80 C. for 3 h. The reaction mixture was admixed with water and ethyl acetate, filtered through kieselguhr and washed through with ethyl acetate. The organic phase was removed, washed with water and saturated aqueous sodium chloride solution, dried over magnesium sulphate and filtered. The filtrate was admixed with silica gel, stirred for 10 min, then filtered and washed through with ethyl acetate. The filtrate was concentrated and the residue was purified via column chromatography (silica gel, eluent: heptane/ethyl acetate 4/1, 2/1, 1/1). The product-containing fractions were concentrated under reduced pressure, and 112 g (77% of theory) of the title compound were obtained. LC-MS (Method 7): Rt=0.81 min; MS (ESIpos): m/z=344 [M+H]+ 1H-NMR (400 MHz, CDCl3) delta [ppm]=1.59 (s, 9H), 5.30 (s, 2H), 7.31-7.39 (m, 3H), 7.42-7.45 (m, 2H), 7.76-7.78 (m, 2H), 7.98-8.12 (dd, 1H). |