Ammonium Chloride → (9S)-2,3-Dimethyl-9-phenyl-5,6,7,8,9,10-hexahydroimidazo[1,2-h][1,7]naphthyridin-7-one

Participants

Reaction Steps

9.7 g (51.6 mmol) of ethyl (S)-3-amino-3-phenylpropionate, 8.5 g (51.6 mmol) of 2,3-dimethyl-6,7-dihydro-5H-imidazo[1,2-a]pyridin-8-one and 0.26 g (1.3 mmol) of p-toluenesulphonic acid monohydrate are heated to reflux in 50 ml of toluene using a water separator. After no more water separates, the reaction mixture is cooled to 0° C. and diluted with 100 ml of tetrahydrofuran. 7.24 g (64.5 mmol) of potassium tert-butoxide are then introduced and the mixture is stirred at room temperature for 16 h. 150 ml of saturated ammonium chloride are added to the reaction mixture, the organic phase is removed and the aqueous phase is extracted with 300 ml of ethyl acetate. The combined organic phases are washed with 250 ml of water, dried over sodium sulphate and evaporated. 13.27 g (88%) of the title compound are isolated as a red-brown oil. An analytical sample is obtained by crystallizing with diethyl ether (red solid, m.p. 134° C.).

Provenance & Evidence