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 one-tenth 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. When the reaction started, the rest of the 3,4-dichlorobromobenzene/diethyl ether solution was added slowly while cooling the reaction mixture to 35-40° C. When all was added, the mixture was stirred at 40° C. for 1 hr, and then cooled to 0° C. To the reaction mixture was added copper(I) iodide (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 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 mixture was washed with aqueous ammonium chloride solution and 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