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With potassium hydroxide In methanol; water; anhydrous toluene (benzene)
Example 1 Preparation of 2,2'-dinitrobibenzyl A catalytic amount of a metal catalyst (0.01 g metal porfin or 0.005 g metal (AcAc)2 +0.01 g crown-ether) was added to a 33percent methanolic KOH-solution, (34 g KOH in 100 ml methanol). The reaction mixture was cooled to 25° C., 2-nitrotoluene (13.7 g, 0.1 mol) was added and air was passed through the reaction mixture, the temperature of the reaction mixture being kept at 25° C. After 12 hours the passsing through of air was interrupted and 150 ml water and 50 ml methanol was added. The reaction mixture was filtered. The filter layer was dissolved in boiling toluene (benzene), was filtered when hot, was cooled and was filtered again. Recrystallisation from ethanol gave a product with m.p. 120°-121° C. Yield 24-27percent. As a by-product o-nitrobenzoic acid was formed.
Reference：
[1] Patent: US4721821, 1988, A,
2
[ 552-16-9 ]
[ 610-71-9 ]
[ 603-78-1 ]
Reference：
[1] Chemische Berichte, 1881, vol. 14, p. 1168,1170
[2] Chemische Berichte, 1881, vol. 14, p. 1168,1170
3
[ 552-16-9 ]
[ 7732-18-5 ]
[ 7726-95-6 ]
[ 636-28-2 ]
[ 610-71-9 ]
[ 603-78-1 ]
Reference：
[1] Chemische Berichte, 1881, vol. 14, p. 1168,1170
With pyrrolidine; In dimethyl sulfoxide; at 25℃; for 78h;
Step 1(E)-4-Oxo-but-2-enoic acid ethyl ester (4.60 mL, 38.32 mmol), 2-nitrobenzoic acid (1.08 g, 6.39 mmol), and pyrrolidine (0.53 mL, 6.39 mmol) were added simultaneously to a solution of commercially available <strong>[18362-30-6]2-chloro-6-hydroxy-benzaldehyde</strong> (5.0 g, 31.93 mmol) in dimethysulfoxide (30 mL) at 25°C and the solution was stirred for 78 hours at 25°C. The reaction was quenched by the addition of water. The reaction mixture was then partitioned between water and ethyl acetate. The combined organics were washed with a saturated brine solution, dried over anhydrous sodium sulfate, filtered, rinsed and concentrated in vacuo. The residue obtained was purified on a silica gel Flash column chromatography using ethyl acetate- hexanes (1 :1.2) as eluents, yielding 5-chloro-3-formyl-2H-chromene-2-carboxylic acid ethyl ester as a solid (2.08 g, 49.5percent).
General procedure: To a solution of 3a (1 g) in ethanol was added Pd/C (5%, 0.1 g) and the mixture was stirred for 24 hrs at room temperature in a hydrogen atmosphere under atmospheric pressure. Insoluble matters were removed using Celite, and the filtrate was concentrated in vacuo to give the desired product 4a (0.76 g) as a yellow solid. To a solution of carboxylic acid (1 equiv) in CH2Cl2 (15 mL) at 0 C was added DMAP (1 equiv) and EDCI (1 equiv). The reaction mixture was stirred at 0 C for 45 minutes. At this time 4a (1 equiv) was added and the mixture was warmed to room temperature and stirred overnight. The resulting mixture was concentrated in vacuo, partitioned between 1.0 M HCl (20 ml) and ethyl acetate (3×20 mL). The combined organic layers were washed with brine (2 × 15 ml), dried over Na2SO4, filtered and concentrated in vacuo. The crude residue was purified by silica gel chromatograph using a mixture of petroleum ether/ethyl acetate (20 : 5, v/v) as eluent to afford the product as a white solid. To a solution of the obtained solid (1 equiv) in 2:3:1 THF/MeOH/H2O (18 ml) was added LiOH·H2O (1.5 equiv). After stirring at room temperature for 4 h, the volatiles were removed under reduced pressure. The residue was acidified with 1N hydrochloric acid solution, and then filtered and the filter cake was washed with 5 mL of water, dried in vacuum to afford a white powder. Recrystallization from 75% EtOH gave the desired compounds 2-17 as white solid.
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