Benzenesulfonic acid, 4-methyl-, compd. with pyridine (1:1) → Tert-butyl 4-(2-chloro-4-hydroxyphenyl)-piperazine-1-carboxylate

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Reaction Steps

A mixture of tert-butyl 4-[2-chloro-4-(tetrahydropyran-2-yloxy)phenyl]piperazine-1-carboxylate (4.73 g, 11.9 mmol) prepared in Reference Example 193 and a catalytic amount of pyridinium p-toluene sulfonate in ethanol (50 ml) was stirred at 70° C. for 1 hour. The reaction mixture was concentrated under reduced pressure, and methylene chloride and saturated sodium hydrogencarbonate aqueous solution were added to the residue, which was stirred for a while. The resulting precipitates were collected by filtration, and dried in vacuo to afford tert-butyl 4-(2-chloro-4-hydroxyphenyl)piperazine-1-carboxylate (2.68 g, yield 72%) as a white powder.

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