Reaction #1124047

Reaction equation

2-amino-5-chloro-benzoic acid methyl ester

3-bromobenzaldehyde

isobutene

ytterbium(III) trifluoromethanesulfonate

→

2-(3-bromo-phenyl)-6-chloro-4,4-dimethyl-1,2,3,4-tetrahydro-quinoline-8-carboxylic acid methyl ester

Yield 21.2%

Solvents

acetonitrile

ethyl acetate

Conditions

Workup

1. 1
   Washwashed with water (100 mL×2) and brine (100 mL×2)
2. 2
   Dryingdried over anhydrous sodium sulfate
3. 3
   OtherThe solvent was removed in vacuo
4. 4
   Otherthe residue was purified by ISCO combi-flash chromatography (gradient elution, 10-30% ethyl acetate in petroleum ether)

Procedure

To a stirred solution of 2-amino-5-chloro-benzoic acid methyl ester (14.5 g, 78.4 mmol) and 3-bromobenzaldehyde (9.2 mL, 78.4 mmol) in acetonitrile (150 mL) were added isobutene (21.0 mL, 313.5 mmol) and ytterbium(III) trifluoromethanesulfonate (Yb(OTf)3) (5.8 g, 9.5 mmol). The resulting mixture was stirred at 85° C. for 18 h in sealed tube. The mixture was diluted with ethyl acetate (300 mL) and washed with water (100 mL×2) and brine (100 mL×2) and then dried over anhydrous sodium sulfate. The solvent was removed in vacuo and the residue was purified by ISCO combi-flash chromatography (gradient elution, 10-30% ethyl acetate in petroleum ether) to afford 2-(3-bromo-phenyl)-6-chloro-4,4-dimethyl-1,2,3,4-tetrahydro-quinoline-8-carboxylic acid methyl ester (6.7 g, 21.2%) as a light yellow oil: LC/MS m/e obsd. (ESI+) [(M+H)+] 408.0 & 410.0.

Source