Iodine → Ethyl 3-(3,4-dichlorophenyl)-1-methylpiperidine-4-carboxylate

Participants

Reaction Conditions

Reaction Steps

To a suspension of magnesium (10.76 g) in diethyl ether (110 mL) was added a trace amount of iodine. About 1/10 amount of a solution of 3,4-dichlorobromobenzene (100 g) in diethyl ether (110 ml) was added slowly at 35-40° C., and the mixture was vigorously stirred until the reaction started. Once the initiation was occurred, the rest of 3,4-dichlorobromobenzene/diethyl ether solution was added slowly with cooling to maintain the reaction temperature at 35-40° C. When everything was added, and the mixture was stirred at 40° C. for 1 hr, then cooled to 0° C. To the reaction mixture was added copper iodide(I) (12.6 g), and the compound (56.2 g) obtained in step 1 was slowly added dropwise at 0° C. The reaction mixture was stirred at 0° C. for 1 hr, and further at room temperature for 1 hr. The reaction mixture was poured into water (40 mL), diethyl ether (500 mL) was added, and the precipitate was removed by decantation. The reaction solution was washed with aqueous ammonium chloride solution and saturated brine and dried, and the solvent was evaporated under reduced pressure. The obtained residue was purified by silica gel column chromatography (solvent gradient; 20% ethyl acetate/hexane→>2.5% aqueous ammonia/17.5% methanol/ethyl acetate) to give crude ethyl 3-(3,4-dichlorophenyl)-1-methylpiperidine-4-carboxylate (cis/trans mixture) (75.5 g) as a brown oil.

Provenance & Evidence