methyl 3-bromoprop-2-ynoate

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a stirred solution of ammonium thiocyanate (3.06 g., 0.04 mole) in 2M aqueous sulfuric acid (20 ml) at 0° C., methyl 3-bromopropiolate (3.26 g., 0.02 mole) was added dropwise, neat, over 5 minutes. After keeping the temperature at 0° C. for 1 hour, the mixture, consisting of a solid precipitate in the aqueous solution, was extracted with ether which was washed with water, dried (MgSO4), and concentrated. The residual solid was suspended in hexane and removed by filtration, yielding 2.4 g. of product. The solid recrystallized from ethanol as yellowish microcrystals; mp 139°-142.5° C.; IR (KBr) 2170, 1680 cm-1. at 0° C. for 1 hour was extracted with ether which was washed with water dried (MgSO4) concentrated removed by filtration yielding 2.4 g The solid recrystallized from ethanol as yellowish microcrystals

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a stirred solution of ammonium thiocyanate (3.06 g., 0.04 mole) in 2M aqueous sulfuric acid (20 ml) at 0° C., methyl 3-bromopropiolate (3.26 g., 0.02 mole) was added dropwise, neat, over 5 minutes. After keeping the temperature at 0° C. for 1 hour, the mixture, consisting of a solid precipitate in the aqueous solution, was extracted with ether which was washed with water, dried (MgSO4), and concentrated. The residual solid was suspended in hexane and removed by filtration, yielding 2.4 g. of product. The solid recrystallized from ethanol as yellowish microcrystals; mp 139°-142.5° C.; IR (KBr) 2170, 1680 cm-1. at 0° C. for 1 hour was extracted with ether which was washed with water dried (MgSO4) concentrated removed by filtration yielding 2.4 g The solid recrystallized from ethanol as yellowish microcrystals

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:95.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Into a 2000-mL 3-necked round-bottom flask was placed methyl 3-bromopropiolate (120 g, 736.33 mmol, 1.00 equiv) and tert-butyl 1H-pyrrole-1-carboxylate (615.61 g, 3.68 mol, 5.00 equiv). The resulting solution was stirred for 30 hr at 95° C. in an oil bath. The reaction mixture was cooled and distilled under reduced pressure (20 mm Hg). The fraction collected at 55° C. was purified by silica gel chromatography (ethyl acetate/petroleum ether, 1:20) to afford 7-tert-butyl 2-methyl 3-bromo-7-azabicyclo[2.2.1]hepta-2,5-diene-2,7-dicarboxylate as a yellow liquid. Into a 2000-mL 3-necked round-bottom flask was placed The reaction mixture was cooled distilled under reduced pressure (20 mm Hg) The fraction collected at 55° C. was purified by silica gel chromatography (ethyl acetate/petroleum ether, 1:20)

Conditions: temp:95.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Into a 2000-mL 3-necked round-bottom flask was placed methyl 3-bromopropiolate (120 g, 736.33 mmol, 1.00 equiv) and tert-butyl 1H-pyrrole-1-carboxylate (615.61 g, 3.68 mol, 5.00 equiv). The resulting solution was stirred for 30 hr at 95° C. in an oil bath. The reaction mixture was cooled and distilled under reduced pressure (20 mm Hg). The fraction collected at 55° C. was purified by silica gel chromatography (ethyl acetate/petroleum ether, 1:20) to afford 7-tert-butyl 2-methyl 3-bromo-7-azabicyclo[2.2.1]hepta-2,5-diene-2,7-dicarboxylate as a yellow liquid. Into a 2000-mL 3-necked round-bottom flask was placed The reaction mixture was cooled distilled under reduced pressure (20 mm Hg) The fraction collected at 55° C. was purified by silica gel chromatography (ethyl acetate/petroleum ether, 1:20)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A 70% solution of ethylamine in water (563 μl) is added dropwise to a mixture of methyl 3-bromopropynoate (632 mg, 2.88 mmol), hydroxylamine hydrochloride (162 mg, 2.33 mmol) and copper (I) chloride (10 mg) in methanol. A solution of 6-ethynylsulphonyl-1,1,4,4,7-pentamethyl-1,2,3,4-tetrahydronaphthalene (Example 7(b)) (500 mg, 1.94 mmol) in methanol (5 ml) is then added dropwise. The reaction medium is stirred for 15 h at room temperature and treated with saturated aqueous ammonium chloride solution and ethyl acetate. The organic phase is washed with water, dried over magnesium sulphate and concentrated. The product is obtained in the form of an oil after purification by flash chromatography on silica (80/20 heptane/CH2Cl2). 1H NMR/CDCl3: 1.26 to 1.28 (s, 12H); 1.67 (s, 4H); 2.35 (s, 3H); 3.78 (s, 3H); 7.14 (s, 1H); 7.48 (s, 1H); 13C NMR/CDCl3: 19.7; CH3/31.8; 4*CH3/34.1; Cq/34.3; Cq/34.9; 2*CH2/52.9; CH3/71.7; CH/72.1; CH/80.2; Cq/124.5; Cq/127.6; Cq/12.8.3; CH/129.3; CH/134.8; Cq/144.6; Cq/146.2; Cq/153.4; Cq. The organic phase is washed with water dried over magnesium sulphate concentrated The product is obtained in the form of an oil after purification by flash chromatography on silica (80/20 heptane/CH2Cl2)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a stirred solution of ammonium thiocyanate (3.06 g., 0.04 mole) in 2M aqueous sulfuric acid (20 ml) at 0° C., methyl 3-bromopropiolate (3.26 g., 0.02 mole) was added dropwise, neat, over 5 minutes. After keeping the temperature at 0° C. for 1 hour, the mixture, consisting of a solid precipitate in the aqueous solution, was extracted with ether which was washed with water, dried (MgSO4), and concentrated. The residual solid was suspended in hexane and removed by filtration, yielding 2.4 g. of product. The solid recrystallized from ethanol as yellowish microcrystals; mp 139°-142.5° C.; IR (KBr) 2170, 1680 cm-1. at 0° C. for 1 hour was extracted with ether which was washed with water dried (MgSO4) concentrated removed by filtration yielding 2.4 g The solid recrystallized from ethanol as yellowish microcrystals

Conditions: temp:0.00; pressure:0.00; stir: