Isobutylene → 2-(2,5-Dichloro-phenyl)-4,4-dimethyl-1,2,3,4-tetrahydro-quinoline-6-carboxylic acid methyl ester

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Reaction Conditions

Reaction Steps

To a stirred solution of 4-aminobenzoic acid methyl ester (1.5 g, 10 mmol) and 2,5-dichloro-benzaldehyde (1.8 g, 10 mmol) in MeCN (5 mL) were added isobutene (2.1 mL, 30 mmol) and ytterbium(III) trifluoromethanesulfonate (Yb(OTf)3) (1.3 g, 2 mmol). The resulting mixture was stirred at 80° C. for 18 hours in sealed tube. The mixture was diluted with water (50 mL), extracted with diethyl ether (50 mL×3). The extracts were washed with water (100 mL) and brine (100 mL) and then dried over anhydrous Na2SO4. The solvent was removed in vacuo and the residue was purified by ISCO combi-flash chromatography (gradient elution, 0-10% ethyl acetate in petroleum ether) to 2-(2,5-dichloro-phenyl)-4,4-dimethyl-1,2,3,4-tetrahydro-quinoline-6-carboxylic acid methyl ester (1.8 g, 50%) as a light yellow solid (reference: Kiselyov, A. S. et al., Tetrahedron 54 (1998) 5089): MS (ESI+) [(M+H)+] 364.2.

Provenance & Evidence