Z. Bai, et al.
Bioorganic&MedicinalChemistryxxx(xxxx)xxx–xxx
Calcd. for C19H15ClO3S3 [M+H]+: 422.9969; found 422.9950.
Compound 9 A solution of ethanolamine (2.44 g, 40 mmol) in tet-
rahydrofuran (200 mL) and EDC·HCl(1.84 g, 9.6 mmol), HOBT(1.08 g,
8.0 mmol) was stirred at room temperature and to it nicotinic acid
(1.0 g, 8.0 mmol) was added in several portions. Upon completion of
the reaction, the solution was washed with distilled water once
(100 mL). Extraction of the ester was effected with chloroform (×3).
The combined chloroform extracts were dried on anhydrous Na2SO4,
decanted and evaporated. Purification was obtained by chromato-
graphy on flash silica (chloroform/methanol 20/1). Compound A4
(0.76 g) was obtained as a yellow oil. Yield: 59%.1 IR (KBr,cm−1):
3330(s), 2924(s), 1541(vs), 1165(m), 1014(m), 736(m). 1H NMR
(400 MHz, CDCl3-d) δ 9.01(s, 1H), 8.65(s, 1H), 8.14(d, J = 6.6 Hz, 1H),
7.49(s, 1H), 7.36(s, 1H), 3.92(s, 1H), 3.83(s, 2H), 3.62(s, 2H). 13C NMR
(101 MHz, CDCl3-d) δ 166.3, 151.8, 147.7, 135.6, 130.2, 123.7, 61.4,
42.8. ESI-HRMS(m/z): Calcd. for C8H10N2O2 [M+H]+: 167.0732;
found 167.0821.
(101 MHz, CDCl3-d) δ 191.7, 170.2 , 161.3, 157.2, 153.6, 140.2, 136.0,
134.9, 130.1, 128.6, 118.9, 72.1, 60.3, 43.54. ESI-HRMS(m/z): Calcd.
for C16H17N3O3S [M+H]+: 332.1081; found 332.1069.
Compound 14 Yield: 67%. IR(KBr,cm−1): 3330(s), 2931(s),
1664(m), 1513(vs), 1489(vs), 1340(vs), 1183(s), 829(m), 736(m). 1H
NMR(400 MHz, CDCl3-d) δ 8.53(s, 1H), 8.14(s, 1H), 7.26(s, 2H), 7.20(s,
2H), 6.97(s, 1H), 6.82(s, 2H), 4.72(t, J = 5.1 Hz, 2H), 3.86–3.71(m,
2H), 1.49(s, 6H). 13C NMR(101 MHz, CDCl3-d) δ 186.1, 173.8, 151.5,
142.6, 138.2, 128.2, 127.6, 125.7, 123.9, 122.1, 121.3, 80.8, 69.3,
37.1, 23.9. ESI-HRMS(m/z): Calcd. for C19H19Cl2N3O5S [M+Na]+
:
494.0413; found 494.0422
Compound A5 Yield: 67%. IR(KBr,cm−1): 3328(s), 2963(s),
1513(vs), 1368(s), 1153 (s), 896(m), 736(m). 1H NMR(400 MHz,
CDCl3-d) δ 7.24(d, J = 8.8 Hz, 2H), 6.87(d, J = 8.8 Hz, 2H), 3.73(d,
J = 10.1 Hz, 2H), 3.47(q, J = 5.5 Hz, 2H), 2.66(s, 1H), 2.17(s, 1H),
1.49(s, 6H). 13C NMR(101 MHz, CDCl3-d) δ 175.7, 152.7, 129.2, 128.6,
122.7, 81.8, 62.1, 42.2, 24.9. ESI-HRMS(m/z): Calcd. for C12H16ClNO3
[M+H]+: 258.0876; found 258.0897.
A4 (100 mg, 0.6 mmol) was combined with 2-chloro-4-nitrophenyl
isothiocyanate (129 mg, 0.6 mmol) in anhydrous THF (30 mL) at 0 °C,
followed by the addition of DBU (106 mg, 0.7 mmol). The resultant
mixture was stirred at 0 °C for 20 min, after which the ice bath was
removed, and the reaction mixture was stirred at room temperature
until the completion of the reaction indicated by TLC. The crude pro-
duct was purified by column chromatography (chloroform/methanol,
30/1). Compound 9(157 mg) as a yellow oil was obtained. Yield: 69%.
IR(KBr,cm−1): 3330(s), 2924(s), 1649(s), 1513(vs), 1340(vs), 1196(m),
894(m), 736(m). 1H NMR(400 MHz, CDCl3-d) δ 9.25(s, 1H), 8.75(s,
1H), 8.55(s, 1H), 8.31(s, 1H), 8.22(d, J = 7.8 Hz, 1H), 8.16(d,
J = 11.6 Hz, 1H), 7.52(s, 1H), 7.26(s, 2H), 4.87(t, J = 5.1 Hz, 2H), 3.96
(d, J = 5.2 Hz, 2H). 13C NMR(101 MHz, CDCl3-d) δ 191.2, 171.3, 166.9,
154.1, 151.6, 139.2, 133.5, 132.3, 131.6, 129.1, 115.8, 69.4, 43.2. ESI-
HRMS(m/z): Calcd. for C15H13ClN4O4S [M+Na]+: 403.0260; found
403.0244.
Compound 15 Yield: 76%. IR(KBr,cm−1): 3244(s), 2965(s),
1666(vs), 1487(vs), 1340(m) , 1060(s), 941(m), 732(m). 1H NMR
(400 MHz, Chloroform-d) δ 8.75(s, 1H), 7.39(s, 1H), 7.13(d, J = 7.6 Hz,
2H), 7.04(s, 1H), 6.88(s, 1H), 6.77(t, J = 8.7 Hz, 2H), 6.71(s, 1H),
6.59–6.50(m, 1H), 4.58(d, J = 15.9 Hz, 2H), 3.62(q, J = 5.5 Hz, 2H),
1.39(d, J = 12.3 Hz, 6H). 13C NMR(101 MHz, CDCl3-d) δ 188.3, 176.4,
164.5, 152.6, 133.9, 129.9, 126.5, 121.4, 117.2, 88.6, 69.7, 39.3, 24.2.
ESI-HRMS(m/z): Calcd. for C19H20ClFN2O3S [M+H]+
: 411.0967;
found 411.0945.
Compound 16 Yield: 71%. IR(KBr,cm−1): 3224(s), 2965(s),
1666(vs), 1593(m), 1487(vs), 1397(s), 1261(s), 1153(s), 1092(s),
963(m), 732(m). 1H NMR(400 MHz, CDCl3-d) δ 8.35(s, 1H), 7.75(s,
1H), 7.38–7.29(m, 1H), 7.19(s, 1H), 7.12(d, J = 8.0 Hz, 4H), 6.91(s,
1H), 6.72(s, 2H), 4.63(s, 2H), 3.65(s, 2H), 1.39(s, 6H). 13C NMR
(101 MHz, CDCl3-d) δ 188.5, 175.6, 151.7, 138.3, 130.2, 129.6, 129.1,
124.5, 121.4, 82.3, 68.4, 38.1, 24.3. ESI-HRMS(m/z): Calcd. for
The procedure and workup of compounds 10–18 were similar to the
process of compound 9 and the procedure and workup of compound A5
were similar to the process of compound A4.
C
19H21ClN2O3S [M+Na]+: 415.0895; found 415.0859.
Compound 17 Yield: 63%. IR(KBr,cm−1): 3246(s), 2939(s),
Compound 10 Yield: 74%. IR(KBr,cm−1): 3330(s), 2931(s), 1593(s),
1513(vs), 1327 (vs), 1154(m), 736(m). 1H NMR(400 MHz, CDCl3-d) δ
9.27(s, 1H), 8.76(s, 1H), 8.55(s, 1H), 8.31(s, 1H), 8.22(d, J = 7.9 Hz,
1H), 8.16(d, J = 11.5 Hz, 1H), 7.52(s, 1H), 7.26(s, 2H), 4.88(t,
J = 5.1 Hz, 2H), 3.98 (d, J = 5.2 Hz, 2H). 13C NMR(101 MHz, CDCl3-d)
δ 190.5, 170.2, 168.4, 155.6, 152.3, 138.1, 135.2, 133.6, 132.9, 128.6,
1646(vs), 1513(vs), 1401(s), 1299(s), 1092(s), 963(m), 655(m). 1H
NMR(400 MHz, CDCl3-d) δ 8.17 (s, 1H), 7.31(s, 1H), 7.13(d, J = 7.1 Hz,
3H), 6.97(s, 2H), 6.91(s, 1H), 6.75(d, J = 22.4 Hz, 2H), 4.62(s, 2H),
3.70–3.57(m, 2H), 2.19(s, 3H), 1.39(s, 6H). 13C NMR(101 MHz, CDCl3-
d) δ 186.3, 174.2, 153.1, 140.4, 137.6, 130.2, 129.6, 126.4, 125.9,
122.6, 86.5, 68.3, 37.6, 23.9, 23.2. ESI-HRMS(m/z): Calcd. for
115.2, 71.8, 41.4. ESI-HRMS(m/z): Calcd. for
C
15H14FN3O2S [M
C
20H23ClN2O3S [M+Na]+: 429.1032; found 429.1016.
+Na]+: 342.0693; found 342.0688.
Compound 18 Yield: 74%. IR(KBr,cm−1): 3246(s), 2991(s),
Compound 11 Yield: 76%. IR(KBr,cm−1): 3331(s), 2957(s), 1649(s),
1513(vs), 1340 (vs), 1181(m), 771(m). 1H NMR(400 MHz, CDCl3-d) δ
8.54(s, 1H), 7.77(s, 1H), 7.35(s, 1H), 7.22(d, J = 6.7 Hz, 2H), 7.19(s,
2H), 7.11–7.06(m, 2H), 6.69(t, J = 7.4 Hz, 1H), 6.62(d, J = 7.6 Hz,
1H), 3.87–3.69(m, 2H), 3.55(s, 2H). 13C NMR(101 MHz, CDCl3-d) δ
190.8, 173.2, 158.4, 154.6, 140.1, 136.9, 136.2, 133.6, 132.9, 128.5,
1666(vs), 1595(m), 1513(vs), 1487(s), 1248(s), 1168(s), 1034(s),
829(m), 734(m). 1H NMR(400 MHz, CDCl3-d) δ 8.70(s, 1H), 8.03(s,
1H), 7.13(s, 2H), 7.00(d, J = 8.2 Hz, 2H), 6.79(s, 2H), 6.69(s, 2H),
4.60(s, 2H), 3.72(s, 1H), 3.66(s, 1H), 3.63(s, 3H), 1.37(s, 6H). 13C NMR
(101 MHz, CDCl3-d) δ 186.8, 174.2, 157.4, 152.6, 133.1, 129.2, 127.6,
125.6, 121.8, 114.8, 84.2, 68.9, 56.7, 38.0, 23.6. ESI-HRMS(m/z):
Calcd. for C20H23ClN2O4S [M+H]+: 423.1167; found 423.1145.
125.6, 70.6, 42.3. ESI-HRMS(m/z): Calcd. for C15H15N3O2S [M+Na]+
:
324.0796; found 324.0783.
Compound 12 Yield: 68%. IR(KBr,cm−1): 3330(s), 2924(s), 1652(s),
1541(vs), 1340 (vs), 1096(m), 689(m). 1H NMR(400 MHz, CDCl3-d) δ
9.13(s, 1H), 8.86(s, 1H), 8.73(s, 1H), 8.19(s, 1H), 7.58–7.47(m, 2H),
7.25(d, J = 8.5 Hz, 1H), 6.92(d, J = 8.4 Hz, 1H), 6.78(d, J = 8.7 Hz,
1H), 4.62(s, 2H), 3.75(s, 2H), 2.25(s, 3H). 13C NMR(101 MHz, CDCl3-d)
δ 190.8, 169.4, 160.7, 155.4, 152.1, 137.6, 136.6, 134.09, 132.7,
129.6, 128.4, 71.6, 61.4, 23.4. ESI-HRMS(m/z): Calcd. for C16H17N3O2S
[M+Na]+: 338.0943; found 338.0939.
4.3. H2S measurement
A 5 mM solution of Na2S in sodium phosphate buffer (20 mM, pH
7.4) was prepared (Na2S·9H2O, 120.20 mg in 100 mL volumetric flask)
and used as the stock solution. Aliquots of 50, 100, 200, 400, 600, 800,
1000, 1500 µL of the Na2S stock solution were added into a 50 mL
volumetric flask and dissolved in sodium phosphate buffer to obtain the
standard solutions in 5, 10, 20, 40, 60, 80, 100, 150 µM, respectively.
1 mL aliquot of the respective solution was reacted with the methylene
blue (MB+) cocktail: 30 mM FeCl3 (200 µL) in 1.2 M HCl, 20 mM of
N,N-dimethyl-1,4- phenylenediamine sulfate (200 µL) in 7.2 M HCl, 1%
w/v of Zn(OAc)2 (100 µL) in H2O at room temperature for at least
15 min (each reaction was performed in triplicate). The absorbance of
Compound 13 Yield: 74%. IR(KBr,cm−1): 3354(s), 2931(s), 1651(s),
1543(vs), 1343 (vs), 1154(m), 736(m). 1H NMR(400 MHz, CDCl3-d) δ
10.99(d, J = 24.6 Hz, 1H), 9.02(d, J = 13.5 Hz, 1H), 8.86(s, 1H),
8.72(d, J = 4.0 Hz, 1H), 8.19(dd, J = 14.2 Hz, 1H), 7.55–7.46(m, 2H),
7.24(d, J = 8.5 Hz, 1H), 6.92(d, J = 8.4 Hz, 1H), 6.71(d, J = 8.5 Hz,
1H), 4.62(d, J = 21.3 Hz, 2H), 3.74(s, 2H), 3.36(s, 3H). 13C NMR
methylene blue was measured at
λmax = 670 nm in UV–Vis
10