tert-Butyl piperazine-1-carboxylate → 3-[4-(tert-Butoxycarbonyl)piperazin-1-yl]-5-(pentafluoro-lambda6-sulphanyl)benzoic acid

Participants

Reaction Conditions

Reaction Steps

3.0 g (9.2 mmol) of the compound of Example 15A and 2.05 g (11.0 mmol) of tert-butyl piperazine-1-carboxylate were initially charged in 80 ml of toluene and the mixture was degassed with argon. 135 mg (0.18 mmol) of [2-(2-aminoethyl)phenyl](chloro)palladiumdicyclohexyl-(2′,4′,6′-triisopropylbiphenyl-2-yl)phosphane/tert-butyl methyl ether adduct, 87.5 mg (0.18 mmol) of dicyclohexyl(2′,4′,6′-triisopropylbiphenyl-2-yl)phosphane and 2.1 g (22.0 mmol) of sodium tert-butoxide were added successively to this solution. The mixture was stirred at 110° C. for 3 h. After this, another 67.8 mg (0.09 mmol) of [2-(2-aminoethyl)phenyl](chloro)palladiumdicyclohexyl-(2′,4′,6′-triisopropylbiphenyl-2-yl)phosphane/tert-butyl methyl ether adduct and 43.8 mg (0.09 mmol) of dicyclohexyl(2′,4′,6′-triisopropylbiphenyl-2-yl)phosphane were added and the mixture was stirred at 110° C. for a further 3 h. The hot mixture was then filtered through kieselguhr, and the mother liquor was concentrated on a rotary evaporator. The residue was suspended in 50 ml of pH 7 buffer solution and the precipitated solid was filtered off. The filter cake was washed with water and dried under reduced pressure. The residue was triturated with 20 ml of methylene chloride, the suspension was filtered again and the filter cake was once more dried under reduced pressure. This gave 2.98 g (72% of theory) of the title compound.

Provenance & Evidence