4-[4-(tert-Butoxycarbonyl)piperazino]benzoic acid

A mixture of compound 2 (3.2 g, 10 mmol) and 2M NaOH (50 mE) in THF (50 ml) and EtOH (50 mE) was stirred at 60° C. for 3 hours. The mixture was concentrated to obtain a residue, HC1 (2 M) was added to adjust pH to 7, filtered to give compound 3 as a white solid (3.0 g, 100percent).A mixture of 16a (4.0 g, 12.5 mmol), in THF (125 mL) and MeOH (31 mL) wasstirred room temperature until a clear solution was obtained, followed by theaddition of 1 N NaOH (125 mL) was added. The mixture was stirred at 50 °C for4 hours after which TLC indicated completed consumption of 16a. The reactionmixture was cooled to room temperature and then poured into an aqueoussolution of HCl (1 M, 200 mL) resulting in the formation of a white precipitate.The mixture was left to stir at room temperature for 30 minutes and theprecipitate was collected via filtration, washed with water (15 mL), and air driedfor 24 hours to give 16b as a white solid (3.17 g, 83percent).1H NMR (400 MHz, DMSO-d6): δ 1.42 (s, 9H), 3.24 – 3.36 (m, 4H), 3.39 – 3.51(m, 4H), 6.96 (d, J = 8.8 Hz, 1H), 7.78 (d, J = 8.8 Hz, 1H). 13C NMR (100 MHz, DMSO-d6): δ 28.65, 47.23, 79.67, 114.22, 120.33, 131.45, 154.11, 154.46, 167.81.(b)To a solution of sodium salt of 4-(piperazin-1-yl)benzoic acid (0.36g, 1.5 mmol) and potassium carbonate (0.20g, 1.5mmol) in 3mL of water di-tert-butyl dicarbonate (0.32g, 1.5 mmol) was added as a solution in 1.8mltetrahydrofuran, dropwise at 0 °C. After the addition was completed, the reaction mixture was allowed to cometo room temperature and stirred for 4 h. THF was removed in vacuum and the aqueous phase was washed withether. The aqueous phase was separated and adjusted to pH 2 with 1 N hydrochloric acid, and extracted with ethylacetate. The combined organic extracts were concentrated to get 4-(4-(tert-butoxycarbonyl)piperazin-1-yl)benzoic acid (0.13 g, 45percent) as a white solid.

Molecular Weight:306.36
XLogP3:2.2
Hydrogen Bond Donor Count:1
Hydrogen Bond Acceptor Count:5
Rotatable Bond Count:4
Exact Mass:306.15795719
Monoisotopic Mass:306.15795719
Topological Polar Surface Area:70.1
Heavy Atom Count:22
Complexity:403
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes