rel-(2R,6S)-2,6-dimethylpiperazine → 2-Ethoxy-5-(cis-2,6-dimethypiperazin-4-ylsulphonyl) benzoic acid

Participants

Reaction Steps

In a 250 ml three-neck flask, 52.6 g (0.23 mol) of cis-2,6-dimethylpiperazine was added to the suspension of compound (II) (53 g, 0.20 mol) in water (170 ml) at about 10° C. with stirring, at the same time the temperature of reacting mixture was kept below 20° C. The reaction was then stirred at 10° C. for another 2 hours. The precipitate was filtered, ice-water washed, dried, and refluxed in acetone for 1 hour, and purified, gave 48 g compound (III) (yield 70%) as white crystalline, m.p. 260.5-273.0° C. (Dec.). HNMR(DMSO) δ: 7.72-7.75(2H, H-4 and H-6 on benzene ring), 7.26-7.28(1H, H-3 on benzene ring), 4.12-4.17(2H, —CH2— on —OCH2CH3), 3.5-3.53(2H, —CH2— on piperazine ring), 2.89-2.92(2H, —CH— on piperazine ring), 1.80-1.86(2H, —CH2— on piperazine ring), 1.31-1.34(3H, —CH3 on —OCH2CH3), 1.0-1.04(6H, two —CH3 groups on piperazine ring).

Provenance & Evidence