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Stage #1: With hydrogenchloride; sodium nitrite In water at 0 - 20℃; Stage #2: With sodium acetate In water; acetone at 0 - 20℃;
A solution of hydrochloric acid (37percent, 13 mL) in water (5.5 mL) was added to 4-bromoaniline (7.48 g, 43.52 mmol) at r.t. with vigorous stirring and the formed precipitate was allowed to stir for 30 min. The reaction mixture was cooled to 0 °C and a solution of sodium nitrite (3.30 g, 47.87 mmol) in water (9 mL) was added dropwise. At the end of diazotization, a clear yellow solution was obtained. Maleimide (8.45 g, 87.05 mmol) in acetone (35 mL) was added dropwise at 0 °C and then the pH of the solution was adjusted to 3-3.5 by adding sodium acetate. CuCl2 (0.88 g, 6.57 mmol) was added to the vigorously stirred mixture. The reaction mixture was stirred at 0 °C for Ih and overnight at r.t. After completion of the reaction as confirmed by TLC, solvents were removed in vacuo to afford the crude compound, which was purified by column chromatography (silica gel, 4: 6 EtOAc: Pet. ether) to afford the title compound as a yellow solid (5.8 g, 57percent). ESIMS (m/z): 252.3 (M+l)
57%
Stage #1: With hydrogenchloride In water at 20℃; for 0.5 h; Stage #2: With sodium nitrite In water Stage #3: With sodium acetate; copper dichloride In water; acetone at 0 - 20℃;
Step 1: Preparation of 3-(4-bromophenyl)-1H-pyrrole-2,5-dioneA solution of hydrochloric acid (37percent, 13 mL) in water (5.5 mL) was added to 4-bromoaniline (7.48 g, 43.52 mmol) at r.t. with vigorous stirring and the formed precipitate was allowed to stir for 30 min. The reaction mixture was cooled to 0° C. and a solution of sodium nitrite (3.30 g, 47.87 mmol) in water (9 mL) was added dropwise. At the end of diazotization, a clear yellow solution was obtained. Maleimide (8.45 g, 87.05 mmol) in acetone (35 mL) was added dropwise at 0° C. and then the pH of the solution was adjusted to 3-3.5 by adding sodium acetate. CuCl2 (0.88 g, 6.57 mmol) was added to the vigorously stirred mixture. The reaction mixture was stirred at 0° C. for 1 h and overnight at r.t. After completion of the reaction as confirmed by TLC, solvents were removed in vacuo to afford the crude compound, which was purified by column chromatography (silica gel, 4:6 EtOAc:Pet. ether) to afford the title compound as a yellow solid (5.8 g, 57percent).ESIMS (m/z): 252.3 (M+1)
Reference：
[1] Journal of the American Chemical Society, 1955, vol. 77, p. 2313
[2] Patent: WO2007/22935, 2007, A1, . Location in patent: Page/Page column 34
With sodium acetate; copper dichloride; In water; acetone; at 0 - 20℃;pH 3 - 3.5;
Preparation 1: 3-(4-bromophenyl)-1H-pyrrole-2,5-dione (P1) A solution of hydrochloric acid (37percent, 27 ml.) in water (11 ml_) was added to 4-bromo aniline (15 g) at room temperature with vigorous stirring and the formed precipitate was allowed to stir for further 30 minutes. Temperature was reduced to 0 0C and a solution of sodium nitrite (6.60 g) in water (17 ml_) was added dropwise to the stirred suspension. At the end of diazotisation, a clear yellow solution was obtained. Maleimide (16.90 g) in acetone (70 mL) was added dropwise at 0 0C and then the pH of the solution was adjusted to 3-3.5 by adding sodium acetate. Copper (II) chloride (1.76 g) was added to the vigorously stirred mixture. The reaction mixture was allowed to stir at 0 0C for 1 h and overnight at room temperature. Acetone was removed in vacuo, the residue was filtered and dried overnight in vacuo to give the crude title compound (14.12 g) which was used without further purification.MS (mlz): 251 [M-H]".
(1R,5S/1S,5R)-1-(4-bromo-phenyl)-3-aza-bicyclo[3.1.0]hexane-2,4-dione[ No CAS ]
Yield
Reaction Conditions
Operation in experiment
Preparation 2: (1/?,5S/1S,5/?)-1-(4-bromophenyl)-3-azabicyclo[3.1.0]hexane-2,4- dione (P2) Milled potassium hydroxide (6.29 g) was added in small portions to a stirred solution of trimethylsulfoxonium iodide (24.66 g) in anhydrous DMSO (224 mL). The resulting mixture was allowed to stir at room temperature for 1.5 h then 3-(4-bromophenyl)-1 H-pyrrole-2,5- dione (P1 , 14.12 g) dissolved in DMSO (90 mL) was then added dropwise and the resulting mixture was allowed to stir at room temperature for 20 minutes. Reaction temperature was brought to 0 °C and aqueous saturated NH4CI (150 mL) was slowly added, followed by Et2O (200 mL). After separation of the two phases, the aqueous layer was repeatedly extracted with Et2O (3 x 100 mL). Combined organic layers were washed with brine and then dried over Na2SO4. Evaporation of the solvent gave the crude title compound (9.61 g) which was used without further purification.MS (mlz): 265.1 [M-H]".
A solution of hydrochloric acid (37percent, 13 mL) in water (5.5 mL) was added to 4-bromoaniline (7.48 g, 43.52 mmol) at r.t. with vigorous stirring and the formed precipitate was allowed to stir for 30 min. The reaction mixture was cooled to 0 °C and a solution of sodium nitrite (3.30 g, 47.87 mmol) in water (9 mL) was added dropwise. At the end of diazotization, a clear yellow solution was obtained. Maleimide (8.45 g, 87.05 mmol) in acetone (35 mL) was added dropwise at 0 °C and then the pH of the solution was adjusted to 3-3.5 by adding sodium acetate. CuCl2 (0.88 g, 6.57 mmol) was added to the vigorously stirred mixture. The reaction mixture was stirred at 0 °C for Ih and overnight at r.t. After completion of the reaction as confirmed by TLC, solvents were removed in vacuo to afford the crude compound, which was purified by column chromatography (silica gel, 4: 6 EtOAc: Pet. ether) to afford the title compound as a yellow solid (5.8 g, 57percent). ESIMS (m/z): 252.3 (M+l)
57%
Step 1: Preparation of 3-(4-bromophenyl)-1H-pyrrole-2,5-dioneA solution of hydrochloric acid (37percent, 13 mL) in water (5.5 mL) was added to 4-bromoaniline (7.48 g, 43.52 mmol) at r.t. with vigorous stirring and the formed precipitate was allowed to stir for 30 min. The reaction mixture was cooled to 0° C. and a solution of sodium nitrite (3.30 g, 47.87 mmol) in water (9 mL) was added dropwise. At the end of diazotization, a clear yellow solution was obtained. Maleimide (8.45 g, 87.05 mmol) in acetone (35 mL) was added dropwise at 0° C. and then the pH of the solution was adjusted to 3-3.5 by adding sodium acetate. CuCl2 (0.88 g, 6.57 mmol) was added to the vigorously stirred mixture. The reaction mixture was stirred at 0° C. for 1 h and overnight at r.t. After completion of the reaction as confirmed by TLC, solvents were removed in vacuo to afford the crude compound, which was purified by column chromatography (silica gel, 4:6 EtOAc:Pet. ether) to afford the title compound as a yellow solid (5.8 g, 57percent).ESIMS (m/z): 252.3 (M+1)
To a solution of 3-(4-bromophenyl)-lH-pyrrole-2,5-dione (3.45 g, 13.74 mmol) obtained in Step 1 of Intermediate IX, in toluene (50 mL) was added ethyldiazoacetate (4.27 mL, 41.23 mmol). The reaction mixture was heated to reflux for 18h. After completion of the reaction as confirmed by TLC, solvent was removed in vacuo to afford crude product which was purified by column chromatography (silica gel, 4: 6 EtOAc: Pet. ether) to afford the title compound as a yellow solid (2.66 g, 57percent).ESIMS (m/z): 338.7(M+1)
57%
In toluene; for 18h;Reflux;
Step 2: Preparation of ethyl 1-(4-bromophenyl)-2,4-dioxo-3-aza-bicyclo[3.1.0]hexane-6-carboxylateTo a solution of <strong>[21724-96-9]3-(4-bromophenyl)-1H-pyrrole-2,5-dione</strong> (3.45 g, 13.74 mmol) obtained in Step 1 of Intermediate IX, in toluene (50 mL) was added ethyldiazoacetate (4.27 mL, 41.23 mmol). The reaction mixture was heated to reflux for 18 h. After completion of the reaction as confirmed by TLC, solvent was removed in vacuo to afford crude product which was purified by column chromatography (silica gel, 4:6 EtOAc:Pet. ether) to afford the title compound as a yellow solid (2.66 g, 57percent).ESIMS (m/z): 338.7 (M+1)
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