Benzenesulfonic acid, 4-methyl-, compd. with pyridine (1:1) → tert-Butyl 4-(3-hydroxyphenyl)piperazine-1-carboxylate

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Reaction Steps

A mixture of tert-butyl 4-[3-(tetrahydropyran-2-yloxy)phenyl]piperazine-1-carboxylate (5.20 g, 14.4 mmol) prepared in Reference Example 199 and a catalytic amount of pyridinium p-toluene sulfonate in ethanol (100 ml) was stirred at 70° C. for 1.5 hours. The reaction mixture was concentrated under reduced pressure, and methylene chloride and a saturated sodium hydrogencarbonate aqueous solution were added to the residue, which was stirred for a while. The resulting precipitates were collected by filtrasion, and then dried in vacuo to afford tert-butyl 4-(3-hydroxyphenyl)piperazine-1-carboxylate (3.73 g, yield 93%) as a a pale brown powder.

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