Methyl 4-Formylbenzoate → 4-[(4-Cyclohexylphenylimino)methyl]benzoic acid methyl ester

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Reaction Steps

Methyl 4-formylbenzoate (47 g, 285 mmol) was dissolved in methanol (400 mL) and a solution of 4-cyclohexylaniline (50 g, 0.285 mmol) in methanol (200 mL) is slowly added with mechanical stirring. More methanol (1 L) was added and the suspension was stirred at room temperature for 3 days. Filtration, washing and drying in vacuo afforded 90.7 g (99%) of 4-[(4-cyclohexylphenylimino)methyl]benzoic acid methyl ester. This was dissolved in N-methylpyrrolidone (855 mL) and methanol (45 mL). With mechanical stirring sodium borohydride pellets (42.4 g, 1.12 mol) was added in portions keeping the temperature below 40° C. The mixture was then stirred at room temperature for 2 hours and at 40° C. for 16 hours. The mixture was cooled to 5° C. and water (2 L) was slowly added. Then acetone (350 mL) was added and the mixture was stirred at 5° C. for 1 hour. Filtration, washing with water (2×500 mL) and drying in vacuo afforded 78 g (86%) of 4-[(4-cyclohexylphenylamino)-methyl]benzoic acid methyl ester as a solid.

Provenance & Evidence