| 82.5% |
In water; at 100℃; for 12.0h; |
Synthesis of 5-dimethylamino-2-thiophenecarboxyaldehyde (30) 5-Bromo-2-thiophenecarboxyaldehyde (1 g, 5.23 mmol) and dimethylamine (1.64 mL, 15.69 mmol) were mixed, followed by addition of purified water (3 mL). The mixture was reacted at 100C for 12 h, and then the layers were separated with chloroform (50 mL x 2) and purified water (50 mL), the chloroform layer was dried with anhydrous sodium sulfate, and then the solvent was evaporated under reduced pressure. The residue was subjected to medium-pressure preparative chromatography using ethyl acetate/hexane (1/1) as an elution solvent to obtain Compound 30. Yield 670 mg (yield rate 82.5%). 1H NMR (300 MHz, CDCl3) delta 3.10 (s, 6H), 5.96 (s, 1H), 7.45 (s, 1H), 9.44 (s, 1H). |
| Ca. 60% |
With toluene-4-sulfonic acid; In water; at 100℃; for 24.0h; |
To a 100 mL round bottom flask was added 5-bromothiophene-2-carbaldehyde (6 g, 32 mmol)And dimethylamine aqueous solution (16.2 mL, content 40%, 128 mmol)To a solution of p-toluenesulfonic acid (0.55 g, 3.2 mmol) as a catalyst,The reaction was refluxed at 100 C for about 24 h,Dimethylamine is volatile,Add about 8 mL of dimethylamine aqueous solution every 6 hours,Process point board tracking,Until 5-bromothiophene-2-carbaldehyde is completely reacted;After completion of the reaction, the mixture was cooled to room temperature,Down to about 60 mL of deionized water,Stirred at room temperature for 0.5 h,Extracted with 3 x 40 mL of dichloromethane;After extraction, the organic phase was combined,Dried over anhydrous sodium sulfate,Filter,Steaming concentrated solution;Using silica gel column chromatography separation and purification (eluent:Ethyl acetate / petroleum ether = 1/1),Finally, a dark red target product (yield of about 60%) was obtained. |
| Ca. 60% |
With toluene-4-sulfonic acid; In water; at 100℃; for 24.0h; |
6 g of 5-bromothiophene-2-carbaldehyde and 16.2 mL of a 40% aqueous solution of dimethylamine were added to a round bottom flask equipped with a condensing device. 0.5 g of p-toluenesulfonic acid was added as a catalyst. The reaction was carried out by heating to 100 C. During the process, the raw material was monitored for 5-bromothiophene-2-ylformaldehyde. The dimethylamine was volatile, and a certain amount of dimethylamine aqueous solution was added every 6 hours until the reaction of 5-bromothiophene-2 formaldehyde was complete, and the reaction took about 24 hours; After completion, it was cooled to room temperature, 60 mL of deionized water was added, stirred for 0.5 h, and then extracted with dichloromethane; the organic phase was combined, dried over anhydrous sodium sulfate for 24 h, then filtered, and concentrated by rotary evaporation; The method was separated and purified (eluent ethyl acetate: petroleum ether = 1:1, Rf = 0.2) to give red 5-(dimethylamino)thiophene-2-carbaldehyde in a yield of about 60%. |
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