反应详情

Sodium 2-((4-acetamidophenoxy)carbonylthio)ethanesulfonic acid (14) was prepared by adapting the General Method for the Reaction of Alkali Metal Salts of Amino Acid Derivatives with 4-Acetamidophenyl 4-Nitrophenyl carbonate (3) to install the thiocarbonate functionality. Under a nitrogen atmosphere and at room temperature, a solution of 4.94 g (30.1 mmol) of commercially available sodium-2-mercaptoethane sulfonate (10) (1H NMR (300 MHz, D2O): δ 2.98 (t, J=7.2 Hz, 2H), 2.67 (t, J=7.2 Hz, 2H) ppm) in approximately 25 mL of degassed water was drop-wise added to a solution of 4-acetamidophenyl 4-nitrophenyl carbonate (3) (9.92 g, 31.4 mmol) in 300 mL of acetonitrile (MeCN). Solid sodium hydrogencarbonate (NaHCO3) (1.15 g, 13.7 mmol was subsequently added in small portions over 30 minutes. The reaction mixture turned turbid (white) and after about 45 minutes it turned green. The reaction course was followed by analytical LC/MS. The reaction was stirred overnight at room temperature. Upon completion of the reaction, the reaction mixture was diluted with dichloromethane (DCM) (175 mL) and water (25 mL) where upon the reaction mixture turned clear. The resulting two layers were separated and the organic layer containing some of the targeted product (14), unreacted 4-acetamidophenyl-4-nitrophenyl carbonate (3), and by-products bis(4-acetamidophenyl) carbonate (dimer carbonate), 4-nitrophenol, and N-(4-hydroxyphenyl)acetamide (1) was discarded. The aqueous layer which contained the desired product was concentrated to dryness under reduced pressure using a rotary evaporator. Acetonitrile (MeCN) (100 mL) was added to the green residue whereupon a solid was formed. The solid was filtered off using a Büchner-funnel and the resulting filter residue was subsequently washed with diethylether (Et2O) (2×25 mL) and with hexanes (3×20 mL). The solid obtained was dried in high vacuum to afford 7.84 g (82% yield) the target compound (14) as yellow solid (99% purity by analytical HPLC). The yellow solid was suspended in a mixture of isopropyl alcohol (iPrOH, IPA)/Ethyl acetate (EtOAc) (400 mL; 1:2 v/v) containing distilled water (20 mL). The supernatant was decanted and the remaining solid was again treated with iPrOH/EtOAc (300 mL; 1:2 v/v) containing distilled water (25 mL). The layers were separated and the aqueous layer was extracted with iPrOH/EtOAc (200 mL; 1:2 v/v). The combined organic solvents were removed under reduced pressure using a rotary evaporator to furnish 2.5 g (25% yield) of the target product (14) as a pale yellow solid. The aqueous layer was concentrated to dryness under reduced pressure using a rotary evaporator and at about 50° C. to afford another 4.2 g (41% yield) of product (14). Absolute ethanol (EtOH) (10 mL) was added to the batch of compound (14) obtained from the organic extracts (2.5 g) followed by slow addition of distilled water (3 mL) while heating the flask to about 55° C. until a clear solution formed. The solution was allowed to cool for about two (2) hours during which time the target compound (14) crystallized out. The crystals were filtered off using a Büchner-funnel and the resulting filter residue was subsequently washed with EtOH (2×5 mL), diethyl ether (2×20 mL) and hexanes (3×20 mL) to afford 1.6 g (16% yield) of thiocarbonate (14) as colorless crystals after drying in high vacuum. To further remove chloride traces (positive AgNO3 test), the crystals were washed with a cold mixture of ethanol (EtOH)/water (9:1 v/v; 20 mL) and dried under reduced pressure to afford 995 mg (10% yield) of the title compound (14) as colorless crystals. Analytical RP-HPLC: 100% purity. Rt=8.62 min. 1H NMR (300 MHz, D2O): δ 7.24 (d, J=9.0 Hz, 2H), 6.99 (d, J=9.0 Hz, 2H), 3.08-3.00 (m, 4H), 1.96 (s, 3H) ppm. LC/MS (ESI): m/z=660.8 [2M+Na]+.

1. customSodium 2-((4-acetamidophenoxy)carbonylthio)ethanesulfonic acid (14) was prepared
2. customUpon completion of the reaction
3. customThe resulting two layers were separated
4. additionthe organic layer containing some of the targeted product (14), unreacted 4-acetamidophenyl-4-nitrophenyl carbonate (3), and by-products bis(4-acetamidophenyl) carbonate (dimer carbonate), 4-nitrophenol, and N-(4-hydroxyphenyl)acetamide (1)
5. concentrationwas concentrated to dryness under reduced pressure
6. customa rotary evaporator
7. additionAcetonitrile (MeCN) (100 mL) was added to the green residue whereupon a solid
8. customwas formed
9. filtrationThe solid was filtered off
10. filtrationthe resulting filter residue
11. washwas subsequently washed with diethylether (Et2O) (2×25 mL) and with hexanes (3×20 mL)
12. customThe solid obtained
13. customwas dried in high vacuum