3-Methyl-2-nitrobenzoic acid → (1Z)-3-imino-3-(3-methyl-4-nitrophenyl)-1-[2-(propyloxy)phenyl]prop-1-en-1-amine

Beteiligte Stoffe

Reaktionsschritte

A solution of 1,1,1-trimethyl-N-(trimethylsilyl)silanamine (2.70 g, 16.8 mmol) in dry tetrahydrofuran (40 mL) was cooled to −78° C., at which time was added n-butyllithium 1.6 N (10.5 mL, 16.8 mmol) followed by commercially available acetophenone (5.50 g, 31 mmol). The reaction mixture was stirred for 1 h at −78° C. to give the 1-[2-(propyloxy)phenyl]ethanone lithium salt. Concurrent with the above was prepared a solution of 1-[(3-methyl-4-nitrophenyl)carbonyl]-1H-imidazole by adding 1,1′-carbonylbis(1H-imidazole) (2.70 g, 16.8 mmol) to 3-methyl-2-nitrobenzoic acid (2.50 g, 14.0 mmol) in tetrahydrofuran (40 mL) at room temperature. To the 1-[2-(propyloxy)phenyl]ethanone lithium salt solution was slowly added the 1-[(3-methyl-4-nitrophenyl)carbonyl]-1H-imidazole solution at −78° C. and the mixture was allowed to warm to room temperature. The reaction mixture was quenched with hydrochloric acid 1.0 N (100 mL) and the product was extracted with ethyl acetate (150 mL). The organic phase was washed with brine (80 mL), dried over anhydrous sodium sulfate, filtered and concentrated in vacuo. The residue was purified by flash chomatography (SiO2, ethyl acetate/hexanes 1:2), followed by re-crystallization from diethyl ether and hexanes (1:5) to afford (1Z)-3-imino-3-(3-methyl-4-nitrophenyl)-1-[2-(propyloxy)phenyl]prop-1-en-1-amine (2.20 g, 46%).

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