Triphenylarsine → 1,1-Dimethylethyl 3′,6′-dihydro[3,4′-bipyridine]-1′(2′H)-carboxylate

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Reaction Steps

tert-Butyl 4-{[(trifluoromethyl)sulfonyl]oxy}-3,6-dihydropyridine-1(2H)-carboxylate (prepared according to Wustrow, D. J., Wise, L. D., Synthesis, (1991), 993-995; 2.73 g, 8.22 mmol) was dissolved in 80 mL of NMP. Triphenylarsine (220 mg, 0.66 mmol), LiCl (1.09 g, 24.7 mmol), and tris(dibenzylideneacetone)-dipalladium(0) (156 mg, 0.160 mmol) were then added to the reaction vessel. After 10 min of constant stirring, tributylstannyl pyridine (4.0 g, 9.7 mmol) in 10 mL of NMP was added using a syringe. The reaction vessel was repeatedly evacuated and flushed with N2 (g) (4×). The reaction mixture was then stirred at rt for 30 min, then at 80° C. for 2.5 h, and then at 65° C. for 16 h. Afterwards, 20 mL of 1M KF solution was added. The mixture was stirred for 1.5 h and then diluted with ethyl acetate (100 mL) and filtered. The filtrate was further diluted with 200 mL of 1M KF solution and 200 mL of ethyl acetate. The organic and aqueous layers were separated, and the aqueous layer was extracted once again with ethyl acetate (200 mL). The organic layers were combined, washed with water (6×200 mL) and then with brine (1×300 mL), dried over sodium sulfate, filtered, and concentrated under reduced pressure. Tert-Butyl 3′,6′-dihydro-3,4′-bipyridine-1′(2′H)-carboxylate was obtained through silica gel flash column chromatography (1% MeOH in EtOAc). ESI-MS calculated for C15H20N2O2: 260.35, found 261 (M+H).

Provenance & Evidence