1,8-Diazabicyclo(5.4.0)undec-7-ene → Benzyl 4-(2-methoxy-2-oxoethyl)-3,6-dihydropyridine-1(2H)-carboxylate

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Reaction Steps

A solution of benzyl 4-(2-methoxy-2-oxoethylidene)piperidine-1-carboxylate (5.25 g, 18.1 mol) and 1,8-diazabicyclo[5.4.0]undec-7-ene (2.71 mL, 18.1 mol) in DMF (120 mL) was stirred at room temperature. After 3 d the reaction was diluted with water and extracted with ether (4×). The organic washes were combined, dried over MgSO4, filtered and concentrated under reduced pressure. The crude product was purified by silica gel chromatography, eluting with a gradient of 5 to 30% ethyl acetate:hexanes to give the title compound (2.44 g). MS: m/z=290.1 (M+1). 1H NMR (500 MHz, CDCl3) δ 7.30-7.25 (m, 5H), 5.5 (brs, 1H), 5.2 (s, 2H), 4.0 (brs, 2H), 3.7 (s, 3H), 3.6 (brs, 2H), 3.0 (s, 2H), 2.2 (brs, 2H).

Provenance & Evidence