3,5-dibromooxane-2,6-dione

反应条件: temp:0.00; pressure:0.00; stir:

反应条件: temp:0.00; pressure:0.00; stir:

反应条件: temp:0.00; pressure:0.00; stir:

反应条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: 2.18 g (8 mmol) of 2,4-dibromoglutaric anhydride, 2.1 ml (20 mmol) of benzyl alcohol, and 2 ml of benzene are stirred for 1.5 hours at room temperature. 76 mg (0.4 mmol) of p-toluenesulfonic acid monohydrate and 8 ml of benzene are added, and the solution is refluxed under a Dean-Stark trap for 2 hours. Filtration over silica gel and evaporation yields 3.77 g (100%) of dibenzyl 2,4-dibromoglutarate as a colourless oil. 1H NMR (CDl3): δ7.37 (br. s., 10H), 5.21 (narrow AB system, 4H, J=12.5); dl isomer: δ4.55 (dd, 2H, J=6.5, 7.5), 2.69 (dd, 2H, J=6.5, 7.5); meso isomer: δ4.42 (t, 2H, J=7.5), 2.90 (dt, 1H, J=7.5 (t), 14.5 (d)), 2.66 (dt, 1H, J=7.5 (t), 14.5 (d)); dl/meso=6:1. IR (neat): 3034, 1740, 1499, 1456, 1385, 1273, 1154, 750, 696 cm-1. the solution is refluxed under a Dean-Stark trap for 2 hours Filtration over silica gel and evaporation

反应条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: 2.18 g (8 mmol) of 2,4-dibromoglutaric anhydride, 0.83 ml (8 mmol) of benzyl alcohol, and 2 ml of chloroform are stirred for 1 hour at room temperature and for another hour under reflux. 20 ml of benzene and 0.1 ml of DMF are added, the solution is cooled in an ice bath, and 1.05 ml (12 mmol) of oxalyl chloride in 5 ml of benzene is added dropwise. Stirring is continued for 40 min. at 0° C. and 70 min. at room temperature, after which time gas evolution has virtually ceased. Volatiles are evaporated in vacuo, and the residue is taken up in 5 ml of CH2Cl2. This solution is added dropwise with ice cooling to a solution of 1.4 ml (15 mmol) of tert.-butanol, 1.4 ml (10 mmol) of triethylamine, and 19.5 mg (0.16 mmol) of 4-dimethylaminopyridine in 15 ml of CH2Cl2 . After stirring at 0° C. and room temperature for 20 min. each, the mixture is washed with aqueous KHSO4 solution, dried over MgSO4, evaporated, and filtered over silica gel to afford 2.65 g (76%) of benzyl t-butyl 2,4-dibromoglutarate. 1H NMR (CDCl3): δ7.37 (br. s., 5H), 5.22 (2 narrow AB systems, 2H), 1.48 (s, 9H); dl isomer: δ4.54 (t, 1H, J=7.5), 4.39 (t, 1H, J=7.5), 2.63 (t, 2H, J=7.5); meso isomer: δ4.44 (t, 1H, J=7.5), 4.26 (t, 1H, J=7.5), 2.83 (dt, 1H, J=7.5 (t), 15 (d)), 2.59 (dt, 1H, J=7.5 (t), 15 (d)); dl/meso=1:2. IR (neat): 2980, 1736, 1456, 1370, 1266, 1148, 843, 752, 696 cm- 1. under reflux the solution is cooled in an ice bath Volatiles are evaporated in vacuo After stirring at 0° C. and room temperature for 20 min. each, the mixture is washed with aqueous KHSO4 solution dried over MgSO4 evaporated filtered over silica gel

反应条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: 544 mg (2 mmol) Of 2,4-dibromoglutaric anhydride, 0.5 ml of CH2Cl2, and 85 μl (2.1 mmol) of methanol are stirred in a capped vial at room temperature for 5.5 hours, after which time the IR spectrum indicates the absence of starting materials. 5 ml of benzene and 10 μl of DMF are added, the solution is then cooled in an ice bath, and 0.19 ml (2.2 mmol) of oxalyl chloride in 2 ml of benzene are added dropwise. Stirring is continued for 15 min. at 0° C. and for 45 min. at room temperature, after which time gas evolution (HCl, CO, CO2) virtually ceases. Volatiles are evaporated in vacuo, and the residue is taken up in 2 ml of CH2Cl2. This solution is added dropwise with ice cooling to a solution of 0.47 ml(5 mmol) of tert.-butanol, 0.35 ml (2.5 mmol) of triethylamine, and 12.2 mg (0.1 mmol) of 4-dimethylaminopyridine in 3 ml of CH2Cl2. After stirring at 0° C. and room temperature for 20 min. each, the mixture is washed with aqueous KHSO4 solution, dried over MgSO4, evaporated, and filtered over silica gel to afford 410 mg (57%) of t-butyl methyl 2,4-dibromoglutarate. 1H NMR (CDCl3): δ4.52, 4.41, 4.40, 4.27 (each t, 1H, J=7.5), 3.81 (s, 3H), 1.49 (s,9H); dl isomer: δ2.61 (t, 2H, J=7.5); meso isomer: δ 2.83 (dt, 1H, J=7.5 (t), 15 (d)), 2.58 (dt, 1H, J=7.5 (t), 15 (d)); dl/meso=2:1. IR (neat): 2980, 1742, 1437, 1370, 1277, 1150, 843 cm-1. the solution is then cooled in an ice bath Volatiles are evaporated in vacuo After stirring at 0° C. and room temperature for 20 min. each, the mixture is washed with aqueous KHSO4 solution dried over MgSO4 evaporated filtered over silica gel

反应条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: 544 mg (2 mmol) Of 2,4-dibromoglutaric anhydride, 0.5 ml of CH2Cl2, and 85 μl (2.1 mmol) of methanol are stirred in a capped vial at room temperature for 5.5 hours, after which time the IR spectrum indicates the absence of starting materials. 5 ml of benzene and 10 μl of DMF are added, the solution is then cooled in an ice bath, and 0.19 ml (2.2 mmol) of oxalyl chloride in 2 ml of benzene are added dropwise. Stirring is continued for 15 min. at 0° C. and for 45 min. at room temperature, after which time gas evolution (HCl, CO, CO2) virtually ceases. Volatiles are evaporated in vacuo, and the residue is taken up in 2 ml of CH2Cl2. This solution is added dropwise with ice cooling to a solution of 0.47 ml(5 mmol) of tert.-butanol, 0.35 ml (2.5 mmol) of triethylamine, and 12.2 mg (0.1 mmol) of 4-dimethylaminopyridine in 3 ml of CH2Cl2. After stirring at 0° C. and room temperature for 20 min. each, the mixture is washed with aqueous KHSO4 solution, dried over MgSO4, evaporated, and filtered over silica gel to afford 410 mg (57%) of t-butyl methyl 2,4-dibromoglutarate. 1H NMR (CDCl3): δ4.52, 4.41, 4.40, 4.27 (each t, 1H, J=7.5), 3.81 (s, 3H), 1.49 (s,9H); dl isomer: δ2.61 (t, 2H, J=7.5); meso isomer: δ 2.83 (dt, 1H, J=7.5 (t), 15 (d)), 2.58 (dt, 1H, J=7.5 (t), 15 (d)); dl/meso=2:1. IR (neat): 2980, 1742, 1437, 1370, 1277, 1150, 843 cm-1. the solution is then cooled in an ice bath Volatiles are evaporated in vacuo After stirring at 0° C. and room temperature for 20 min. each, the mixture is washed with aqueous KHSO4 solution dried over MgSO4 evaporated filtered over silica gel

反应条件: temp:0.00; pressure:0.00; stir:

反应条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: 2.18g (8 mmol) of 2,4-dibromoglutaric anhydride, 2.1 ml (20 mmol) of benzyl alcohol, and 2 ml of benzene are stirred for 1 5 hours at room temperature 76 mg (0.4 mmol) of p-toluenesulfonic acid monohydrate and 8 ml of benzene are added, and the solution is refluxed under a Dean-Stark trap for 2 hours. Filtration over silica gel and evaporation yields 3.77g (100%) of dibenzyl 2,4-dibromoglutarate as a colourless oil. 1H NMR (CDCl3): δ7.37 (br. s., 10H), 5.21 (narrow AB system, 4H, J=12.5); dl isomer: δ4.55 (dd, 2H, J=6.5, 7.5), 2.69 (dd, 2H, J=6.5, 7.5); meso isomer: δ 4.42 (t, 2H, J=7.5), 2.90 (dt, 1H, J=7.5 (t), 14.5 (d)), 2.66 (dt, 1H, J=7.5 (t), 14.5 (d)); dl/meso=6:1. IR (neat): 3034, 1740, 1499, 1456, 1385, 1273, 1154, 750, 696 cm-1. are added the solution is refluxed under a Dean-Stark trap for 2 hours Filtration over silica gel and evaporation

反应条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: 10.0g (34.5 mmol) of 2,4-dibromoglutaric acid and 4.9 ml (69 mmol) of acetyl chloride are refluxed for a period of 2 hours. Volatiles are removed at 10 torr up to 90° C., and the residue bulb-to-bulb distilled (75°-90° C./0.25 torr), yielding 8.9g (95%) of a colourless, viscous oil. 1H NMR (CDCl3): dl isomer: δ 4.90 (t, 2H, J=6), 2.87 (t, 2H, J=6); meso isomer: 4.77 (dd, 2H, J=6, 10), 3.15 (dt, 1H, J=6 (t), 15 (d)), approx. 2.85 (1H, partially overlapping); dl/meso=5:1. IR (neat): 3007, 2942, 1817, 1775, 1439, 1242, 1109, 1038, 972, 932, 847, 691, 617 cm-1. Volatiles are removed at 10 torr up to 90° C. the residue bulb-to-bulb distilled (75°-90° C./0.25 torr) yielding 8.9g (95%) of a colourless, viscous oil

反应条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: 544 mg (2 mmol) of 2,4-dibromoglutaric anhydride, 0.5ml of CH2Cl2, and 85 μl (2.1 mmol) of methanol are stirred in a capped vial at room temperature for 5.5 hours, after which time the IR spectrum indicates the absence of starting materials. 5 ml of benzene and 10 μl of DMF are added, the solution is then cooled in an ice bath, and 0.19 ml (2.2 mmol) of oxalyl chloride in 2 ml of benzene are added dropwise. Stirring is continued for 15 min. at 0° C. and for 45 min. at room temperature, after which time gas evolution (HCl, CO, CO2) virtually ceases. Volatiles are evaporated in vacuo, and the residue is taken up in 2 ml of CH2Cl2. This solution is added dropwise with ice cooling to a solution of 0.47 ml(5 mmol) of tert.-butanol, 0.35 ml (2.5 mmol) of triethylamine, and 12.2 mg (0.1 mmol) of 4-dimethylaminopyridine in 3 ml of CH2Cl2. After stirring at 0° C. and room temperature for 20 min. each, the mixture is washed with aqueous KHSO4 solution, dried over MgSO4, evaporated, and filtered over silica gel to afford 410 mg (57%) of t-butyl methyl 2,4-dibromoglutarate. 1H NMR (CDCl3): δ4.52, 4.41, 4.40, 4.27 (each t, 1H, J=7.5), 3.81 (s, 3H), 1.49 (s,9H); dl isomer: δ2.61 (t, 2H, J=7.5); meso isomer: δ 2.83 (dt, 1H, J=7.5 (t), I5 (d)), 2.58 (dt, 1H, J=7.5 (t), 15 (d)); dl/meso=2:1. IR (neat): 2980, 1742, 1437, 1370, 1277, 1150, 843 cm-1. the solution is then cooled in an ice bath Volatiles are evaporated in vacuo After stirring at 0° C. and room temperature for 20 min. each, the mixture is washed with aqueous KHSO4 solution dried over MgSO4 evaporated filtered over silica gel

反应条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: 2.18 g (8 mmol) of 2,4-dibromoglutaric anhydride, 2.1 ml (20 mmol) of benzyl alcohol, and 2 ml of benzene are stirred for 1.5 hours at room temperature. 76 mg (0.4 mmol) of p-toluenesulfonic acid monohydrate and 8 ml of benzene are added, and the solution is refluxed under a Dean-Stark trap for 2 hours. Filtration over silica gel and evaporation yields 3.77 g (100%) of dibenzyl 2,4-dibromoglutarate as a colourless oil. 1H NMR (CDl3): δ7.37 (br. s., 10H), 5.21 (narrow AB system, 4H, J=12.5); dl isomer: δ4.55 (dd, 2H, J=6.5, 7.5), 2.69 (dd, 2H, J=6.5, 7.5); meso isomer: δ4.42 (t, 2H, J=7.5), 2.90 (dt, 1H, J=7.5 (t), 14.5 (d)), 2.66 (dt, 1H, J=7.5 (t), 14.5 (d)); dl/meso=6:1. IR (neat): 3034, 1740, 1499, 1456, 1385, 1273, 1154, 750, 696 cm-1. the solution is refluxed under a Dean-Stark trap for 2 hours Filtration over silica gel and evaporation