Sodium ethoxide → tert-Butyl 2-phenyl-7,8-dihydropyrido[4,3-d]pyrimidine-6(5H)-carboxylate

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Reaction Steps

A mixture of 3-dimethylaminomethylene-4-oxo-piperidine-1-carboxylic acid tert-butyl ester (prepared according to the method of Example 101, Step B, 509 mg, 2.0 mmol), benzamidine hydrochloride hydrate (470 mg, 3.0 mmol), and sodium ethoxide (1 M in ethanol, 6.0 mL, 6.0 mmol) in absolute ethanol (4 mL) was heated to reflux for about 3 d, cooled to room temperature, and concentrated. The residue was diluted with saturated aqueous sodium bicarbonate and extracted with chloroform (3×). The combined organic extracts were dried over sodium sulfate, filtered, evaporated, and purified by flash column chromatography (Biotage Flash 40S™, 10→15% ethyl acetate/hexanes) to give 304 mg (49%) of the title compound of Example 101, Step C as a yellow oil. 1H NMR (CDCl3, 400 MHz) δ 8.52 (s, 1H), 8.40-8.38 (c, 2H), 7.50-7.44 (c, 3H), 4.62 (s, 2H), 3.78 (t, 2H) 3.02 (t, 2H), 1.50 (s, 9H); MS (APCI) 312 (MH+).

Provenance & Evidence