Tetrahydrofuran → Methyl 2-(3-(benzyl oxycarbonyl)phenyl)-4-hydroxy-3,3-dimethyl-1,2,3,4-tetrahydroquinoline-6-carboxylate

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Reaction Steps

To a solution of (E)-benzyl 3-((4-(methoxycarbonyl)phenylimino)methyl)benzoate (15.0 g, 40.1 mmol, 1.0 eq.), yttrium(III) trifluoromethanesulfonate (0.5 g, 0.8 mmol, 0.02 eq.) in Tetrahydrofuran (85 mL) in a four-necked flask was added Isobutyl aldehyde (3.18 g, 44.2 mmol, 1.1 eq.) via syringe. The reaction mixture was stirred at room temperature under nitrogen overnight. Thin layer chromatography (Petroleum ether:ethyl acetate=6:1) showed the reaction was complete. The reaction mixture was washed with water and the aqueous layer was extracted with ethyl acetate (twice). The organic layers were washed with brine, dried over anhydrous sodium sulfate. The solvent was removed in vacuo and the residue was purified by column chromatography (Petroleum ether:ethyl acetate=5:1, then 2:1) to afford 14.2 g of methyl 2-(3-(benzyl oxycarbonyl)phenyl)-4-hydroxy-3,3-dimethyl-1,2,3,4-tetrahydroquinoline-6-carboxylate as a yellow solid, which was used in next step without further purification. Yield: 78.9%. MS (ESI+APCI) M−17=428.1.

Provenance & Evidence