Hydrochloric Acid → 1-Carbethoxy-4-hydroxy-4-[2-(4-methylphenylsulfanyl)phenyl]piperidine

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Reaction Steps

In a stirred reactor under nitrogen cover 2-(4-tolylsulfanyl)-phenyl bromide (600 g, 2.15 mol) was suspended in heptane (4.5 L). At room temperature 10M BuLi in hexane (235 mL, 2.36 mol) was added over 10 minutes. Only a small exotherm was noticed. The suspension was stirred for 1 hour at ambient temperature and then cooled down to −40° C. 1-Carbethoxy-4-piperidone (368 g, 2.15 mol) dissolved in THF (1.5 L) was added at a rate not faster than the reaction temperature was kept below −40° C. When the reaction has gone to completion, it was warmed to 0° C. and 1M HCl (1 L) was added keeping the temperature below 10° C. The acid aqueous phase was separated and extracted with ethyl acetate (1 L). The organic phases were combined and extracted with sodium chloride solution (15%, 1 L). The organic phase was dried over sodium sulphate and evaporated to a semi crystalline mass. It was slurried with ethyl ether (250 mL) and filtered off. Dried in a vacuum oven at 40° C. until constant weight.

Provenance & Evidence