p-Toluenesulfonic acid → 1-(2,4-Dichlorophenyl)-3-methyl-5-piperidin-1-yl-1,5,6,7-tetrahydro-pyrrolo[3,2-c]pyridine-4-one

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Reaction Steps

To a solution of 1,1′-bipiperidine-2,4-dione (Example 15) (260 mg, 1.32 mmol) in dry toluene (25 mL) at rt were added 1-[(2,4-dichlorophenyl)amino]acetone (288 mg, 1.32 mmol, prepared in a similar manner to Example 25) followed by p-TSA (p-toluenesulfonic acid) (25 mg, 0.132 mmol). The mixture was heated at reflux with a Dean-Stark trap, and 10 mL toluene was collected in the trap. Then, 1 equiv. of p-TSA (250 mg, 1.32 mmol) was added and the reaction mixture was heated at reflux for 6 h. The cooled reaction was evaporated and the residue purified by flash chromatography using 9:1 CH2Cl2/MeOH as eluant to give the title material as brown solid (215 mg, 43% yield), which was used in Example 18.

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