Water → 4-Hydroxy-2-(3-methoxy-phenyl)-3,3-dimethyl-1,2,3,4-tetrahydro-quinoline-6-carboxylic acid methyl ester

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Reaction Conditions

Reaction Steps

To a stirred mixture solution of 4-[(3-methoxy-benzylidene)-amino]-benzoic acid methyl ester (2.7 g, 10.0 mmol) and ytterbium(III) triflate hydrate (620.3 mg, 1.0 mmol) in dry tetrahydrofuran (10 mL) at 25° C. was added isobutyraldehyde (0.93 mL, 10.2 mmol) and water (0.2 mL, 10.2 mmol) dropwise. The reaction mixture was stirred at 25° C. for 16 h. Then the reaction mixture was concentrated in vacuo and the residue was extracted with ethyl acetate (2×200 mL), washed with brine, dried over anhydrous sodium sulfate and concentrated in vacuo to afford 4-hydroxy-2-(3-methoxy-phenyl)-3,3-dimethyl-1,2,3,4-tetrahydro-quinoline-6-carboxylic acid methyl ester (3.4 g, quant.) as a light yellow oil which was used for next step without further purification: LC/MS m/e calcd for C20H23NO4 (M+H)+: 342.41, observed: 324.2 & 342.2.

Provenance & Evidence