2-Bromo-2'-acetonaphthone → 2-Amino-3-ethoxycarbonyl-5-(naphth-2-yl)-1H-pyrrole

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Reaction Steps

Under an argon atmosphere, 834 mg (5 mmol) of 2-amidino-acetic acid ethyl ester hydrochloride [for preparation see: Liebigs Ann. Chem., 1895 (1977)] are introduced into 10 ml of ethanol and, at 0-5° C., 358 mg (5 mmol) of sodium ethanolate are added thereto. The bright yellow suspension is stirred for 15 min and then 623 mg (2.5 mmol) of 2-bromo-1-(naphth-2-yl)-ethan-1-one (2-bromo-2'-acetonaphthone; Aldrich; Milwaukee/USA) are added thereto. After 3 days' stirring at RT, the reaction mixture is concentrated by evaporation. The residue is taken up in ethyl acetate/water and filtered and the organic phase is separated off and washed with 3 portions of water and brine. The aqueous phases are extracted with ethyl acetate and the organic phases are dried over MgSO4 and concentrated by evaporation. Column chromatography (SiO2 ; ethyl acetate/hexane [1:1]) and stirring in diethyl ether/hexane yield the title compound; m.p. 149-151° C.; TLC-Rf =0.5 (ethyl acetate/hexane [1:1]); FAB-MS: (M+H)+ =281.

Provenance & Evidence