| 17% |
With hydrogenchloride; In ethanol; water; for 36h;Inert atmosphere; Reflux; |
To a stirring mixture of 1 (10.0 g, 20.6 mmol) and concentratedhydrochloric acid (120 mL) in ethanol (120 mL)was added water (10 mL), the reaction mixture was refluxedunder a N2 atmosphere for 36 h. After cooled down to theroom temperature, the mixture was poured into water. Thesolid obtained was filtered followed by silica gel columnchromatographic purification of the residue using 50% ethylacetate in petroleum ether afforded the compound 2 in 17.0%yield as yellow solid. 1H NMR (DMSO-d6, 300 MHz) 12.78 (s, 1H, 5-OH), 10.44 (s, 1H, 4'-OH), 10.29 (s, 1H, 7-OH), 8.71 (s, 1H, 6-OH), 7.90 (d, J = 8.8 Hz, 2H, 2',6'-H),6.91 (d, J = 8.8 Hz, 2H, 3',5'-H), 6.74 (s, 1H, 3-H), 6.57 (s,1H, 8-H); ESI-MS: m/z 287 [M+H]+. |
| 17% |
With hydrogenchloride; In ethanol; water; for 36h;Reflux; Inert atmosphere; |
Concentrated HCl (120 mL) was added into a stirringmixture of 1 (10 g, 21.65 mmol) and water (10 mL) in ethanol(120 mL), the reaction mixture was refluxed for 36 hunder nitrogen, and then was allowed to cool to room temperature.Water (1000 mL) was added, the solid appearedwas filtered, and then purified by column chromatographyon silica gel with 50% ethyl acetate in petroleum ether aseluent to afford 2 (1.05g, 17% yield) as a yellow solid, m. p.225-227 C. 1H NMR: 12.78 (s, 1H, 5-OH), 10.44 (s, 1H,4'-OH), 10.29 (s, 1H, 7-OH), 8.71 (s, 1H, 6-OH), 7.90 (d, J =8.8 Hz, 2H, H-2',6'), 6.91 (d, J = 8.8 Hz, 2H, H-3',5'), 6.74(s, 1H, 3-H), 6.57 (s, 1H, 8-H). ESI-MS: m/z 287 [M+H]+. |
| 17.0% |
With hydrogenchloride; In ethanol; water; for 36h;Inert atmosphere; Reflux; |
4.1.1 5,6,7-Trihydroxy-2-(4-hydroxyphenyl)-4H-chromen-4-one (2) Water (10 ml) was added to a stirring mixture of scutellarin (1) (10.0 g, 21.6 mmol) and concentrated hydrochloric acid (120 ml) in ethanol (120 ml), then the reaction mixture was refluxed under an N2 atmosphere for 36 h. After being cooled down to the room temperature, the mixture was poured into water, the solid obtained was filtered, and purified by column chromatography (50% ethyl acetate in petroleum ether) to afford 2 (1.05 g, 17.0% yield) as a yellow solid. 1H NMR (DMSO-d6, 300 MHz) delta 6.57 (s, 1H, 8-H), 6.74 (s, 1H, 3-H), 6.91 (d, J = 8.8 Hz, 2H, 3',5'-H), 7.90 (d, J = 8.8 Hz, 2H, 2',6'-H), 8.71 (s, 1H, 6-OH), 10.29 (s, 1H, 7-OH), 10.44 (s, 1H, 4'-OH), 12.78 (s, 1H, 5-OH); ESI-MS: m/z 287 [M + H]+. |
| 17% |
With hydrogenchloride; In water; for 36h;Reflux; Inert atmosphere; |
Concentrated HCl (120 mL) was added into a stirring mixture of 1 (10 g, 21.65 mmol) and water (10 mL) in ethanol (120 mL), the reaction mixture was refluxed for 36 h under nitrogen, and then was allowed to cool to room temperature. Water (1000 mL) was added, the solid appeared was filtered, and then purified by column chromatography on silica gel with 50% ethyl acetate in petroleum ether as eluent to afford 2 (1.05 g, 17% yield) as a yellow solid, mp 160-162 C. 1H NMR (DMSO-d6, 300 MHz) d: 6.57 (s, 1H, C3-H),6.74 (s, 1H, C8-H), 6.91 (d, J = 8.8 Hz, 2H, C30C50-H), 7.90 (d,J = 8.8 Hz, 2H, C20C60-H), 8.71 (s, 1H, C6-OH), 10.29 (s, 1H, C7-OH),10.44 (s, 1H, C40-OH), 12.78 (s, 1H, C5-OH). 13C NMR (75 MHz,DMSO-d6) d: 98.53 (C8), 102.27 (C3), 103.22 (C10), 115.76 (2 C(C30,C50)), 121.37 (C10), 124.91 (C6), 128.47 (2 C(C20,C60)),145.42 (C9), 152.98 (C5), 153.28 (C7), 160.99 (C40), 163.47 (C2),181.95 (C4). ESI-MS: m/z 287 [M+H]+. |
| 17% |
With hydrogenchloride; In ethanol; water; for 36h;Inert atmosphere; Reflux; |
Concentrated hydrochloric acid (120 mL) and water (10 mL) were added to a solution of 1 (10.0 g, 21.6 mmol) in ethanol (120 mL), andthe reaction mixture was refluxed for 36 h under a N2 atmosphere. The reaction mixture was cooled to room temperature, and poured into cold water. The solid which appeared was filtered, and was then purified by chromatography on the silica gel column using 50% ethyl acetate in petroleum ether afforded 2 (1.05 g, 17.0% yield) as yellow solid; m.p. 288-290 C (lit.17 290-293 C). 1H NMR (DMSO-d6, 300 MHz) delta 6.57(s, 1H, C8H), 6.74 (s, 1H, C3H), 6.91 (d, J = 8.8 Hz, 2H, C3?,C5?H),7.90 (d, J = 8.8 Hz, 2H, C2?,C6?H), 8.71 (s, 1H, C6OH), 10.29 (s, 1H,C7OH), 10.44 (s, 1H, C4?OH), 12.78 (s, 1H, C5OH); 13C NMR (75MHz, DMSO-d6) delta 98.53 (C8), 102.27 (C3), 103.22 (C10), 115.76(C3?,C5?), 121.37 (C1?), 124.91 (C6), 128.47 (C2?,C6?),145.42 (C9),152.98 (C5), 153.28 (C7), 160.99 (C4?), 163.47 (C2), 181.95 (C4); ESIMS: m/z 287 [M+H]+. Anal. calcd for C15H10O6: C, 62.94; H, 3.52;found: C, 62.92; H, 3.53%. |
| 17% |
With sulfuric acid; water; In ethanol; for 48h;Reflux; Inert atmosphere; |
Concentrated H2SO4 (100 mL) was added into a stirring mixture of 1 (10 g, 21.65 mmol) and water (10 mL) in ethanol (90 mL), and the reaction mixture was refluxed for 48 h under nitrogen and then was allowed to cool to room temperature. Water (1000 mL) was added, and the solid that appeared was filtered and then purified by column chromatography on silica gel with 50% ethyl acetate in petroleum ether as eluent to afford 1 (1.05 g, 17% yield) as a yellow solid. IR (KBr): 3343.24, 1663.08, 1610.20, 1580.85, 1458.41, 1364.24, 1270.26, 1252.35, 1183.51, 1079.25, 1028.97, 1004.24, 830.86, 721.26, 598.71, 574.65 cm-1. 1H-NMR (DMSO-d6) 6.73 (s, 1H, 8-H), delta 6.78 (s, 1H, 3-H), 6.90-6.93 (d, 2H, J = 8.8 Hz, 3?,5?-H), 7.90-7.93 (d, 2H, J = 8.8 Hz, 2?,6?-H), 8.71 (s, 1H, 6-OH), 10.30 (s, 1H, 4?-OH), 10.44 (s, 1H, 7-OH), 12.79 (s, 1H, 5-OH); ESI-MS: m/z 285 [M - H]-; Anal. Calcd. for C15H10O6: C, 62.94; H, 3.52; Found: C, 62.92; H, 3.49. The IR and 1H-NMR spectrums were included in the Supplementary Materials available online. |
| 17% |
With hydrogenchloride; water; In ethanol; for 36h;Reflux; Inert atmosphere; |
To a stirring mixture of 1 (10.0 g, 21.6 mmol)and concentrated hydrochloric acid (120 mL) in ethanol (120 mL) was added water (10 mL), and thereaction mixture was refluxed under a N2 atmosphere for 36 h. After cooling down to room temperature,the mixture was poured into water. The solid obtained was filtered followed by silica gel columnchromatography purification of the residue using 50% ethyl acetate in petroleum ether to affordcompound 2 (1.05 g, 17.0% yield) as yellow solid. 1H-NMR (DMSO-d6) delta 6.57 (s, 1H, 8-H), 6.74 (s,1H, 3-H), 6.91 (d, J = 8.8 Hz, 2H, 3?,5?-H), 7.90 (d, J = 8.8 Hz, 2H, 2?,6?-H), 8.71 (s, 1H, 6-OH), 10.29(s, 1H, 7-OH), 10.44 (s, 1H, 4?-OH), 12.78 (s, 1H, 5-OH); ESI-MS: m/z 287 [M + H]+. |
| 17% |
With hydrogenchloride; In ethanol; water; for 36h;Reflux; Inert atmosphere; |
Concentrated hydrochloric acid (120 mL) and water (10mL) were added into a stirring mixture of 1 (10.0 g, 20.6mmol) in ethanol (120 mL), then this reaction mixture wasrefluxed for 36 h under a N2 atmosphere. The mixture waspoured into water after cooled down to room temperature.The obtained solid was filtered and then purified by silica gelcolumn chromatographic, using 50% ethyl acetate in petroleumether as eluting solvent, thus produced compound 2 asyellow solid. Yield 17.0%. Mp 160-162 C. 1H NMR(DMSO-d6, 300 MHz) : 6.57 (s, 1H, C8-H), 6.74 (s, 1H, C3-H), 6.91 (d, J = 8.8 Hz, 2H, C3'C5'-H), 7.90 (d, J = 8.8 Hz,2H, C2'C6'-H), 8.71 (s, 1H, C6-OH), 10.29 (s, 1H, C7-OH),10.44 (s, 1H, C4'-OH), 12.78 (s, 1H, C5-OH). ESI-MS: m/z287 [M+H]+. |
| 17% |
With hydrogenchloride; In ethanol; water; for 36h;Reflux; Inert atmosphere; |
Scutellarin 1 (10 g, 21.6 mmol) was added to a mixture of 120 mL of absolute ethanol, 120 mL of concentrated hydrochloric acid and 10 mL of H 2 O.Under reflux conditions of N2, reflux for 36 h.After cooling at room temperature, the reaction solution is poured into an equal volume of water, suction filtered, washed with water until neutral, and dried.The crude product was separated by silica gel column chromatography ( petroleum ether: ethyl acetate 1:1).A yellow solid lamp was obtained, 1.0 g of scutellarin aglycone 5, and the yield was 17%. |
| 17% |
With hydrogenchloride; In ethanol; water; at 120℃; for 36h;Inert atmosphere; |
The scutellarin 1 (10 g, 21.6 mmol) to 120 mL of absolute ethanol.A mixture of 120 mL of concentrated hydrochloric acid and 10 mL of H 2 O.Under reflux conditions of N2, reflux for 36 h.After cooling at room temperature, the reaction liquid was poured into an equal volume of water, suction filtered, washed with water until neutral, dried, and the crude product was separated by silica gel column chromatography ( petroleum ether: ethyl acetate 1:1).A yellow solid lamp was obtained, 1.0 g of scutellarin derivative 5, and the yield was 17%. |
| 17% |
With hydrogenchloride; In ethanol; water; for 36h;Reflux; Inert atmosphere; |
Water (10 ml) was added to a stirring mixture of scutel-larin (1) (10.0 g, 21.6 mmol) and concentrated hydrochloric acid (120 ml) in ethanol (120 ml), then the reaction mixture was refluxed under N 2 atmosphere for 36 h. After being cooled down to the room temperature, the mixture was poured into water, the solid obtained was filtered, and puri-fied by column chromatography (50% ethyl acetate in petro-leum ether) to afford 2 (1.05 g, 17% yield) as a yellow solid, Rf = 0.2 (50% ethyl acetate in petroleum ether). 1H NMR (DMSO-d 6 , 300 MHz) delta 6.57 (s, 1H, 8-H), 6.74 (s, 1H, 3-H), 6.91 (d, J = 8.8 Hz, 2H, 3',5'-H), 7.90 (d, J = 8.8 Hz, 2H, 2',6'-H), 8.71 (s, 1H, 6-OH), 10.29 (s, 1H, 7-OH), 10.44 (s, 1H, 4'-OH), 12.78 (s, 1H, 5-OH). ESI-MS: m/z 287 [M+H]+. HRMS (ESI) calcd. for C 15 H 10 O 6 [M + H]+ 287.0556, found 287.0559; calcd. for C 15 H 9 NaO 6 [M + Na]+ 309.0375, found 309.0371. |
| 10.3% |
With sulfuric acid; In ethanol; at 105℃; for 9h;Inert atmosphere; |
(1), take concentrated sulfuric acid, add to 90% ethanol,Prepared into a molar concentration of 3mol / L sulfuric acid ethanol solution, spare;(2), 462 mg of scutellarin was added to the solution of the sulfuric acid ethanol prepared in the step (1)The concentration of scutellarin in sulfuric acid ethanol solution was 23.1 mg / mL,The molar ratio of scutellarin to sulfuric acid was 1:60,And then refluxed under nitrogen protection at 105 C for 9 hours;(3), after the end of the reaction, room temperature cooling, the reaction solution poured into 100mL water, precipitation precipitation, to be completely filtered after pumping,The solid was recrystallized from 80% ethanol solution and 30.1 mg of scented baicalein, yield 10.3%The purity was 97.8% by high performance liquid chromatography. |
|
With sulfuric acid; In ethanol; water; at 120℃; for 48h;Inert atmosphere; |
In a 10 mL round-bottomed flask, 300 mg (0.65 mmol) of scutellarin was dissolved in 5 mL of specific ethanol. To the mixture was added 1 mL of sulfuric acid with a specific concentration (Table 1), and the solution was stirred and heated to a specific temperature (Table 1). The reaction was timed just after the addition of H2SO4. After completion of the reaction, aliquots of the reaction mixture were subjected to HPLC analysis. The mobile phase for HPLC consisted of solvent (A) i.e., and (B), solvent i.e. acetonitrile. The mobile phase consisted of acetonitrile and 0.1% (v/v) formic acid in filtered MilliQ water in the ratio of 24: 76 (v/v) with isocratic elution. The flow rate was 1.0 mL/min. Analytes weremonitored at 254 nm. The injection volume was 10 mL. |
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