Sodium ethoxide → tert-butyl 2-(diethylamino)-4-oxo-5,6,7,9-tetrahydro-1H-pyrimido[4,5-c]azepine-8-carboxylate

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Reaction Steps

To a solution of 3-oxo-azepane-1,4-dicarboxylic acid 1-tert-butyl ester 4-ethyl ester (0.67 g, 2.3 mmol) in EtOH (10 mL) was added diethyl guanidinium trifluoroacetate (0.54 g, 2.3 mmol) and sodium ethoxide (21 wt % in EtOH, 2.3 mL). The reaction was heated at reflux for 16 h then cooled to room temperature (rt). The reaction mixture was diluted with H2O and extracted with CH2Cl2 (2×). The combined organic extracts were dried and concentrated. The resulting material was triturated with hexanes/Et2O (9:1) to give the title compound (0.334 mg, 43%) as a light brown solid. MS (ESI): mass calcd. for C17H28N4O3, 336.4; m/z found, 337.4 [M+H]+. 1H NMR (CDCl3): 4.34-4.25 (m, 2H), 3.62-3.46 (m, 6H), 2.66-2.58 (m, 2H), 1.88-1.77 (m, 2H), 1.50-1.36 (m, 9H), 1.21-1.14 (m, 6H).

Provenance & Evidence