Phosphorus oxychloride → 7-Benzyl-4-chloro-5,6,7,8-tetrahydropyrido[3,4-d]pyrimidine

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Reaction Steps

Part B: To a mixture of 7-benzyl-5,6,7,8-tetrahydropyrido[3,4-d]pyrimidin-4(3H)-one 4.83 g, 20.0 mmol) in toluene (80 mL) at 25° C. was added N,N-diisopropylethylamine (3.48 mL, 20.0 mmol), followed by phosphorous oxychloride (2.24 mL, 24.0 mmol). The reaction mixture was heated at reflux for 2.00 h. After cooling to room temperature, the mixture was diluted with water and ethyl acetate. The aqueous phase was adjusted to ˜pH 7 employing saturated aqueous sodium bicarbonate solution. The phases were separated. The organic phase was washed with water and brine, dried over anhyd. sodium sulfate, filtered, and concentrated. The residue was dissolved in 1-chlorobutane, and the resulting mixture was filtered. The filtrate was concentrated under vacuum to provide 7-benzyl-4-chloro-5,6,7,8-tetrahydropyrido[3,4-d]pyrimidine (4.75 g, 91%) as an orange-red oil; Mass Spec.: m/e: 260.10/262.05 (M+H)+ [calc'd: 260.09/262.08].

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