C([Mg]Br)#C.CON(C)[C:8]([N:10]1[CH2:19][CH2:18][C:17]2[C:12](=[CH:13][CH:14]=[CH:15][CH:16]=2)[CH2:11]1)=O.[Cl-].[NH4+].[O:23]1CC[CH2:25][CH2:24]1>>[CH2:18]1[C:17]2[C:12](=[CH:13][CH:14]=[CH:15][CH:16]=2)[CH2:11][N:10]([C:8]#[C:25][CH:24]=[O:23])[CH2:19]19.08 ml of a 0.5 molar solution of ethynylmagnesium bromide in tetrahydrofuran were added dropwise within 20 min. to a solution of 1 g of 3,4-dihydro-1H-isoquinoline-2-carboxylic acid methoxy-methyl-amide in 5 ml of tetrahydrofuran under argon at 0° C. The reaction mixture was stirred at 0° C. for 1 h. and at room temperature for 1 h. The orange solution was poured into 50 ml of a saturated ammonium chloride solution and extracted twice with 50 ml of ethyl acetate each time. The combined organic phases were washed twice with 50 ml of water each time, once with 50 ml of a saturated sodium chloride solution, dried over magnesium sulfate and concentrated. 0.48 g (57%) of 1-(3,4-dihydro-1H-isoquinolin-2-yl)-propynone was obtained as a yellowish oil. MS (EI): 185M30 .
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