4-ethoxy-4-oxobut-2-ynoate

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

Procedure: A suspension of 14.7 g of 3-amino-5-methyl-s-triazole and 26.8 g of ethyl acetylenedicarboxylate in 120 ml of ethanol was refluxed for three hours, the reaction mixture was allowed to stand at room temperature for one hour, and the formed crystals were collected by filtration. The filtrate was concentrated and the residue was recrystallized from dichloromethane, and the crystals were joined with those obtained above. Purification by silica gel chromatography gave 10.8 g of the objective compound as colorless crystals. was refluxed for three hours the formed crystals were collected by filtration The filtrate was concentrated the residue was recrystallized from dichloromethane those obtained above Purification by silica gel chromatography

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

Procedure: A suspension of 14.7 g of 3-amino-5-methyl-s-triazole and 26.8 g of ethyl acetylenedicarboxylate in 120 ml of ethanol was refluxed for three hours, the reaction mixture was allowed to stand at room temperature for one hour, and the formed crystals were collected by filtration. The filtrate was concentrated and the residue was recrystallized from dichloromethane, and the crystals were joined with those obtained above. Purification by silica gel chromatography gave 10.8 g of the objective compound as colorless crystals. was refluxed for three hours the formed crystals were collected by filtration The filtrate was concentrated the residue was recrystallized from dichloromethane those obtained above Purification by silica gel chromatography

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

Procedure: A suspension of 14.7 g of 3-amino-5-methyl-s-triazole and 26.8 g of ethyl acetylenedicarboxylate in 120 ml of ethanol was refluxed for three hours, the reaction mixture was allowed to stand at room temperature for one hour, and the formed crystals were collected by filtration. The filtrate was concentrated and the residue was recrystallized from dichloromethane, and the crystals were joined with those obtained above. Purification by silica gel chromatography gave 10.8 g of the objective compound as colorless crystals. was refluxed for three hours the formed crystals were collected by filtration The filtrate was concentrated the residue was recrystallized from dichloromethane those obtained above Purification by silica gel chromatography

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

Procedure: Ethyl acetylenedicarboxylate (17.8 ml, 0.145 mol) was added to 2-bromo-4-methoxyphenol (Synlett p 1241, 1997) (27.3 g, 0.134 mol), in anhydrous 2-propanol (55 ml) followed by the addition of a catalytic amount of tetrabutylammonium fluoride (0.4 ml, 1.0 M in THF). The solution was stirred at room temperature overnight and was then heated to reflux for 30 min. Upon cooling a precipitate formed. The solution was cooled and filtered to give diethyl (2Z)-2-(2-bromo-4-methoxyphenoxy)-2-butenedioate as a yellow solid (29.9 g, 62% yield). Note: the solid contains 10% of diethyl (2E)-2-(2-bromo-4-methoxyphenoxy)-2-butenedioate. GC/MS (EI, M+) m/z 344 and 346. was then heated to reflux for 30 min Upon cooling a precipitate formed The solution was cooled filtered

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

Procedure: Ethyl acetylenedicarboxylate (17.8 ml, 0.145 mol) was added to 2-bromo-4-methoxyphenol (Synlett p 1241, 1997) (27.3 g, 0.134 mol), in anhydrous 2-propanol (55 ml) followed by the addition of a catalytic amount of tetrabutylammonium fluoride (0.4 ml, 1.0 M in THF). The solution was stirred at room temperature overnight and was then heated to reflux for 30 min. Upon cooling a precipitate formed. The solution was cooled and filtered to give diethyl (2Z)-2-(2-bromo-4-methoxyphenoxy)-2-butenedioate as a yellow solid (29.9 g, 62% yield). Note: the solid contains 10% of diethyl (2E)-2-(2-bromo-4-methoxyphenoxy)-2-butenedioate. GC/MS (EI, M+) m/z 344 and 346. was then heated to reflux for 30 min Upon cooling a precipitate formed The solution was cooled filtered

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

Procedure: Ethyl acetylenedicarboxylate (17.8 ml, 0.145 mol) was added to 2-bromo-4-methoxyphenol (Synlett p1241, 1997) (27.3 g, 0.134 mol), in anhydrous 2-propanol (55 ml) followed by the addition of a catalytic amount of tetrabutylammonium fluoride (0.4 ml, 1.0 M in THF). The solution was stirred at room temperature overnight and was then heated to reflux for 30 min. Upon cooling a precipitate formed. The solution was cooled and filtered to give diethyl (2Z)-2-(2-bromo-4-methoxyphenoxy)-2-butenedioate as a yellow solid (29.9 g, 62% yield). Note: the solid contains 10% of diethyl (2E)-2-(2-bromo-4-methoxyphenoxy)-2-butenedioate. GC/MS (EI, M+) m/z 344 and 346. was then heated to reflux for 30 min Upon cooling a precipitate formed The solution was cooled filtered

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

Procedure: Ethyl acetylenedicarboxylate (17.8 ml, 0.145 mol) was added to 2-bromo-4-methoxyphenol (Synlett p1241, 1997) (27.3 g, 0.134 mol), in anhydrous 2-propanol (55 ml) followed by the addition of a catalytic amount of tetrabutylammonium fluoride (0.4 ml, 1.0 M in THF). The solution was stirred at room temperature overnight and was then heated to reflux for 30 min. Upon cooling a precipitate formed. The solution was cooled and filtered to give diethyl (2Z)-2-(2-bromo-4-methoxyphenoxy)-2-butenedioate as a yellow solid (29.9 g, 62% yield). Note: the solid contains 10% of diethyl (2E)-2-(2-bromo-4-methoxyphenoxy)-2-butenedioate GC/MS (EI, M+) m/z 344 and 346. was then heated to reflux for 30 min Upon cooling a precipitate formed The solution was cooled filtered

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

Procedure: Ethyl acetylenedicarboxylate (17.8 ml, 0.145 mol) was added to 2-bromo-4-methoxyphenol (Synlett p1241, 1997) (27.3 g, 0.134 mol), in anhydrous 2-propanol (55 ml) followed by the addition of a catalytic amount of tetrabutylammonium fluoride (0.4 ml, 1.0 M in THF). The solution was stirred at room temperature overnight and was then heated to reflux for 30 min. Upon cooling a precipitate formed. The solution was cooled and filtered to give diethyl (2Z)-2-(2-bromo-4-methoxyphenoxy)-2-butenedioate as a yellow solid (29.9 g, 62% yield). Note: the solid contains 10% of diethyl (2E)-2-(2-bromo-4-methoxyphenoxy)-2-butenedioate. GC/MS (EI, M+) m/z 344 and 346. was then heated to reflux for 30 min Upon cooling a precipitate formed The solution was cooled filtered

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

Procedure: A suspension of 14.7 g of 3-amino-5-methyl-s-triazole and 26.8 g of ethyl acetylenedicarboxylate in 120 ml of ethanol was refluxed for three hours, the reaction mixture was allowed to stand at room temperature for one hour, and the formed crystals were collected by filtration. The filtrate was concentrated and the residue was recrystallized from dichloromethane, and the crystals were joined with those obtained above. Purification by silica gel chromatography gave 10.8 g of the objective compound as colorless crystals. was refluxed for three hours the formed crystals were collected by filtration The filtrate was concentrated the residue was recrystallized from dichloromethane those obtained above Purification by silica gel chromatography

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

Procedure: A suspension of 14.7 g of 3-amino-5-methyl-s-triazole and 26.8 g of ethyl acetylenedicarboxylate in 120 ml of ethanol was refluxed for three hours, the reaction mixture was allowed to stand at room temperature for one hour, and the formed crystals were collected by filtration. The filtrate was concentrated and the residue was recrystallized from dichloromethane, and the crystals were joined with those obtained above. Purification by silica gel chromatography gave 10.8 g of the objective compound as colorless crystals. was refluxed for three hours the formed crystals were collected by filtration The filtrate was concentrated the residue was recrystallized from dichloromethane those obtained above Purification by silica gel chromatography