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With manganese(IV) oxide; In dichloromethane; at 40℃; for 2h;
To a solution of 1 (5.0 g, 34 mmol) in DCM was added MnO2(1.3 g, 6.8 mmol). The resulting solution was stirred at 40 C for 2 h and monitored by TLC. Aftercomplete conversion of starting material, reaction mixture was cooled to room temperature, filteredand concentrated in vacuo to obtain 2 as white solid in 85.0% yield. LC-MS m/z: 147.1 [M + H]+.
70%
With [Ru(2,6-bis[1-(pyridin-2-yl)-1H-benzo[d]-imidazol-2-yl]pyridine)(pyridine-2,6-dicarboxylate)]; dihydrogen peroxide; In water; at 50℃; for 5.5h;Catalytic behavior;
The procedure for gram scale oxidation of (1H-benzo[d]imidazol-2-yl)methanol to 1H-benzo[d]imidazole-2-carbaldehydewas as follows: (1H-benzo[d]imidazol-2-yl)methanol (0.1 mol,14.8 g) and [Ru(bpbp)(pydic)] (0.001 mmol, 7.32 × 10-3 g) wereadded into a reactor. The reactor containing this mixture was heatedto 50 C in an oil bath under vigorous stirring and then 30% H2O2(30 mL, 0.3 mol) was slowly dropwise over a period of 30 min. The mixture was stirred for 5 h. After filtering, the solution wasevaporation under reduced pressure at 50 C. Pure 1H-benzo[d]imidazole-2-carbaldehyde (0.07 mmol, 10.2 g) was obtained with ayield of 70% after recrystallisation from 30% H2SO4 solution. Theproduct, 1H-benzo[d]imidazole-2-carbaldehyde, was identified byits 1H NMR spectrum.
57%
With Ru(bpp)(pydic); dihydrogen peroxide; at 50℃;
The method for synthesizing 2-aldehyde benzimidazole in this example is as follows2-Hydroxymethylbenzimidazole (0.1 mol, 14.8 g)The rhodium complex (10-4 mol, 0.0577 g) in Example 1 was added to the reaction vessel.Hydrogen peroxide (30%, 0.3 mol, 9.1 ml) was slowly added to the reaction vessel with stirring.The reaction temperature was controlled at 50C for several hours.The reaction solution was concentrated under reduced pressure,Obtain a solid product,The solid product was dissolved in dichloromethane and subjected to silica gel column chromatography.Get pure product2-aldehyde benzoimidazole 8.32 g,Yield 57%.
51%
With manganese(IV) oxide; In methanol; dichloromethane;
General procedure: To a stirred solution of the (1H-benzo[d]imidazol-2-yl)methanol from above (2.6 mmol) in dryCH2Cl2/MeOH (6:1, 3.5 mL) was added activated manganese dioxide (85% purity, <5 micron, 2.328 g, 22.8 mmol)and the suspension stirred overnight, at which point the black slurry was filtered through a cake of celite andwashed with MeOH (3x5 mL). The combined washings were concentrated to afford a dark brown solid.Purification of the crude product by column chromatography on silica gel (CH2Cl2:MeOH, 98:2 to 95:5) affordedthe title compound 1H-benzo[d]imidazole-2-carbaldehyde (2i) (0.245 g, 51%).
With manganese(IV) oxide; In ethyl acetate; at 65℃; for 1h;
General procedure: A solution of 2a-2d (2 mmol), MnO2 (3.48 g, 40 mmol) was added to EtOAc (120 mL), then refluxedat 65 C for 1 h (monitored by TLC). Afterwards the solution was filtered, and concentrated in vacuoto give pure compounds 3a-3d (in 60%-76% yield) [17].
With manganese(IV) oxide; In dichloromethane; at 40℃; for 2h;
The resulting solid (1H-benzimidazol-2-yl) methanol (34 mmol) was dissolved in 250 mL of dichloromethane and stirredFollowed by addition of manganese dioxide (0.68 mmol). The temperature was raised to 40 C and stirring was continued for 2 hours to monitor the reaction. After the reaction is complete, the product is evaporated to drynessDichloromethane, 150 mL of tetrahydrofuran was added. Directly to the next step
With manganese dioxide; In N-methyl-acetamide; ethanol;
EXAMPLE I STR28 A mixture of 2-Hydroxymethyl-benzimidazole (11.9 g) and MnO2 (59.5 g) in ethanol (250 mL) was vigorously stirred for 2 days. The reaction was concentrated in vacuo, hot dimethylformamide was added and the mixture was filtered through celite. After removal of the solvent in vacuo the tan solid was triturated with ethanol to afford 2-Benzimidazolecarboxaldehyde as a tan powder.
(1H-benzoimidazol-2-yl)methyl 5-bromo-1H-indole-3-carboxylate[ No CAS ]
Yield
Reaction Conditions
Operation in experiment
86%
General procedure: One of compounds 4a-4f (5 mmol) was dissolved in THF (25 mL) and DCC (1.24 g, 6 mmol), and DMAP (0.12 g, 1 mmol) was slowly added and the mixture was stirred for 30 min. Compounds 2a-2c (5 mmol) was added and the mixture was stirred for 7-9 h. The by-product, N,N'-dicyclohexylurea, was removed by filtration. The filtrate was concentrated in vacuum to give a solid which was dissolved in CH2Cl2 and the product 5a-5n was filtered off.
85.95%
To a three-necked flask was added 1.24 g (6 mmol) of dicyclohexylcarbodiimide, 0.12 g (1 mmol) of 4-dimethylaminopyridine was added, followed by addition of 25 mL of tetrahydrofuran. After stirring, 1.20 g of <strong>[10406-06-1]5-bromoindole-3-carboxylic acid</strong> (5 mmol) was added and stirred at room temperature for half an hour. 75 g (5 mmol) 2-hydroxymethyl benzimidazole, And then stirred at room temperature for 8h, stop the reaction, filtration, steaming the filtrate, drying, and then dissolved in methylene chloride, room temperature conditions, standing until a large amount of soil precipitation precipitate, filter, filter cake, vacuum drying 1.59g(1H-benzimidazol-2-yl) methyl-5-bromo-1H-indole-3-carboxylate in a yield of 85. 95%.
(1H-benzoimidazol-2-yl)methyl 2-methyl-1H-indole-3-carboxylate[ No CAS ]
Yield
Reaction Conditions
Operation in experiment
22%
General procedure: One of compounds 4a-4f (5 mmol) was dissolved in THF (25 mL) and DCC (1.24 g, 6 mmol), and DMAP (0.12 g, 1 mmol) was slowly added and the mixture was stirred for 30 min. Compounds 2a-2c (5 mmol) was added and the mixture was stirred for 7-9 h. The by-product, N,N'-dicyclohexylurea, was removed by filtration. The filtrate was concentrated in vacuum to give a solid which was dissolved in CH2Cl2 and the product 5a-5n was filtered off.
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