2-amino-3-chloronaphthalene-1,4-dione

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

Procedure: To a suspension of 5.0 g (24 mmol) of 2-amino-3-chloro-1,4-dihydro-1,4-dioxonaphthalene in 130 mL of water, 8.4 g (35 mmol) of nonahydrated sodium sulfide are added. The reaction mixture is heated to reflux for 20 min, then 50 mL of an aqueous solution containing 1.0 g of sodium sulfate are added. The color of the medium changes completely to blue. 2.60 mL (24 mmol) of 4-fluorobenzaldehyde and 6.36 mL of glacial acetic acid are added successively. After 1 h of reflux, the greenish precipitate obtained is filtered, dried, and purified on a flash column (support: silica; conditioning: heptane; eluant: dichloromethane/heptane, 60/40). The yellow crystals formed after evaporation of the solvent are washed successively with the isopropanol and ether, then uncolored and recrystallized in dichloromethane to produce 2.0 g of 4,9-dihydro-4,9-dioxo-2-(4-fluorophenyl)naphtho[2,3-d]thiazole in the form of yellow crystals. are added The reaction mixture is heated to reflux for 20 min are added After 1 h of reflux the greenish precipitate obtained is filtered dried purified on a flash column (support: silica; conditioning: heptane; eluant: dichloromethane/heptane, 60/40) The yellow crystals formed after evaporation of the solvent are washed successively with the isopropanol and ether uncolored and recrystallized in dichloromethane

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

Procedure: To a suspension of 5.0 g (24 mmol) of 2-amino-3-chloro-1,4-dihydro-1,4-dioxonaphthalene in 80 mL of water, 8.4 g (35 mmol) of nonahydrated sodium sulfide are added. The reaction mixture is then heated to reflux for approximately 20 min, then 20 mL of an aqueous solution containing 2.0 g of sodium sulfide are added. When the color of the medium has completely changed to blue, 1.95 mL (24 mmol) of 2-fluorobenzaldehyde and 6.36 mL of glacial acetic acid are added successively. After 1 h of reflux, the black semisolid product obtained is filtered, dried, and purified on a flash column (support: silica; conditioning: heptane; eluant: dichloromethane/heptane, 50/50). The greenish crystals formed after evaporation of the solvent are washed several times with ethanol and ether, then they are uncolored and recrystallized in dichloromethane to produce 2.0 g of 4,9-dihydro-4,9-dioxo-2-(2-fluorophenyl)-naphtho[2,3-d]thiazole in the form of yellow crystals. are added The reaction mixture is then heated to reflux for approximately 20 min are added are added successively After 1 h of reflux the black semisolid product obtained is filtered dried purified on a flash column (support: silica; conditioning: heptane; eluant: dichloromethane/heptane, 50/50) The greenish crystals formed after evaporation of the solvent are washed several times with ethanol and ether recrystallized in dichloromethane

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

Procedure: To a solution of 5.0 g (24 mmol) of 2-amino-3-chloro-1,4-dihydro-1,4-dioxonaphthalene in 60 mL of dioxane, one adds at ambient temperature 15.3 mL (120 mmol) of 4-chlorobenzoic acid chloride and 0.5 mL of concentrated sulfuric acid. The reaction mixture is heated to reflux for 4 h, then evaporated to dryness, redissolved in 200 mL of dichloromethane, and neutralized at cold temperature with 100 mL of 10N sodium hydroxide. The organic phase is then washed three times with water and dried over calcium chloride. The red powder so obtained is purified on a flash column (support: silica; conditioning: heptane; eluant: dichloromethane/heptane, 70/30). The yellow crystals obtained after evaporation of the solvent are uncolored and recrystallized in dichloromethane to produce 2.5 g of 2-(4-chlorophenyl)-4,9-dihydro-4,9-dioxo-naphtho[2,3-d]oxazole in the form of yellow crystals. The reaction mixture is heated to reflux for 4 h evaporated to dryness redissolved in 200 mL of dichloromethane The organic phase is then washed three times with water dried over calcium chloride The red powder so obtained is purified on a flash column (support: silica; conditioning: heptane; eluant: dichloromethane/heptane, 70/30) The yellow crystals obtained after evaporation of the solvent recrystallized in dichloromethane

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

Procedure: To a solution of 5 g (24 mmol) of 2-amino-3-chloro-1,4-dihydro-1,4-dioxonaphthalene in 60 mL of dioxane, 15.3 mL (120 mmol) of 2-chlorobenzoic acid chloride are added; after 5 min of stirring, 0.5 mL of concentrated sulfuric is added. The reaction mixture is heated to reflux for 4 h, and the precipitate obtained after evaporation of the dioxane at a reduced pressure is dissolved in 200 mL of dichloromethane. To this solution, 100 mL of a cold 10N sodium hydroxide solution are added. The mixture is stirred for 2 h. The organic phase is then extracted, washed several times with water and dried over calcium chloride. The solid residue obtained after evaporation of the solvent is purified on a medium-pressure column (support: silica; eluant: dichloromethane/heptane, 40/60). The product obtained is recrystallized after color removal in a heptane/dichloromethane mixture (1/1) to produce 5 g of 2-(2-chlorophenyl)-4,9-dihydro-4,9-dioxo-naphtho[2,3-d]oxazole in the form of light yellow crystals. 0.5 mL of concentrated sulfuric is added The reaction mixture is heated to reflux for 4 h the precipitate obtained after evaporation of the dioxane at a reduced pressure is dissolved in 200 mL of dichloromethane To this solution, 100 mL of a cold 10N sodium hydroxide solution are added The mixture is stirred for 2 h The organic phase is then extracted washed several times with water dried over calcium chloride The solid residue obtained after evaporation of the solvent is purified on a medium-pressure column (support: silica; eluant: dichloromethane/heptane, 40/60) The product obtained is recrystallized after color removal in a heptane/dichloromethane mixture (1/1)

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

Procedure: To a solution of 5.0 g (24 mmol) of 2-amino-3-chloro-1,4-dihydro-1,4-dioxonaphthalene in 80 mL of dichloromethane, one adds, with protection from light and at ambient temperature, 16 mL (120 mmol) of 4-methoxybenzoic acid chloride, then 0.003 mL of concentrated sulfuric acid. After 3 h of reflux, the reaction mixture is evaporated to dryness; the black oily residue obtained is redissolved in 300 mL of dichloromethane, washed with a solution of 10N sodium hydroxide, then with water, and finally dried over calcium chloride. The product is then purified on a flash column (support: silica 6-35 mm; conditioning: heptane; eluant: dichloromethane/heptane, 60/40), to produce 4.1 g of 4,9-dihydro-4,9-dioxo-2-(4-methoxyphenyl)-naphtho[2,3-d]oxazole in the form of yellow-orangish crystals after recrystallization and color removal with animal charcoal. After 3 h of reflux the reaction mixture is evaporated to dryness the black oily residue obtained washed with a solution of 10N sodium hydroxide with water, and finally dried over calcium chloride The product is then purified on a flash column (support: silica 6-35 mm; conditioning: heptane; eluant: dichloromethane/heptane, 60/40)

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

Procedure: To a solution of 5 g (24 mmol) of 2-amino-3-chloro-1,4-dihydro-1,4-dioxo-naphthalene in 70 mL of dioxane, one adds, with protection from light, 32.00 mL (240 mmol) of 3-methylbenzoic acid chloride; after 5 min of stirring, 0.50 mL of concentrated sulfuric acid is added. After 45 min of reflux and complete cooling, 200 mL of ether are added, and the precipitate that forms is eliminated by filtration. The red filtrate is evaporated to dryness, redissolved in dichloromethane, washed several times with water, dried and purified on a flash column (support: silica; conditioning: heptane; eluant: dichloromethane/heptane, 50/50). The yellow crystals formed after evaporation of the solvent are uncolored and recrystallized in dichloromethane to produce 3 g of 4,9-dihydro-4,9-dioxo-2-(3-methylphenyl)-naphtho[2,3-d]oxazole in the form of yellow crystals. After 45 min of reflux the precipitate that forms is eliminated by filtration The red filtrate is evaporated to dryness redissolved in dichloromethane washed several times with water dried purified on a flash column (support: silica; conditioning: heptane; eluant: dichloromethane/heptane, 50/50) The yellow crystals formed after evaporation of the solvent recrystallized in dichloromethane

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

Procedure: To a solution of 5.00 g (24 mmol) of 2-amino-3-chloro-1,4-dihydro-1,4-dioxonaphthalene in 37 mL (280 mmol) of 2-methylbenzoic acid chloride, 8 drops of concentrated sulfuric acid are added with protection from light. After 7 h of reflux and complete cooling, the ocher precipitate that forms is filtered through fritted glass, washed with ether, and purified on a flash column (support: silica; conditioning: heptane; eluant: dichloromethane/heptane, 50/50). The yellow powder obtained after evaporation of the solvent is uncolored, and recrystallized in dichloromethane to produce 2.34 g of 4,9-dihydro-4,9-dioxo-2-(2-methylphenyl)-naphtho[2,3-d]oxazole in the form of yellow crystals. After 7 h of reflux complete cooling, the ocher precipitate that forms is filtered through fritted glass washed with ether purified on a flash column (support: silica; conditioning: heptane; eluant: dichloromethane/heptane, 50/50) The yellow powder obtained after evaporation of the solvent recrystallized in dichloromethane

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

Procedure: To a solution of 6.22 g (30 mmol) of 2-amino-3-chloro-1,4-dihydro-1,4-dioxo-naphthalene in 60 mL of nitrobenzene, 18.00 mL (150 mmol) of 4-fluorobenzoic acid chloride are added with protection from light. After 10 min of stirring with reflux, 0.20 mL of concentrated sulfuric acid is added. After 12 h and complete cooling, ether is added to obtain a yellow precipitate which is filtered through fritted glass, washed with ether and purified on a flash column (support: silica; conditioning: heptane; eluant: dichloromethane/heptane, 60/40). The yellow powder obtained after evaporation of the solvent is uncolored, recrystallized in dichloromethane to produce 2.90 g of 4,9-dihydro-4,9-dioxo-2-(4-fluorophenyl)-naphtho[2,3-d]oxazole in the form of yellow crystals. with reflux After 12 h to obtain a yellow precipitate which is filtered through fritted glass washed with ether purified on a flash column (support: silica; conditioning: heptane; eluant: dichloromethane/heptane, 60/40) The yellow powder obtained after evaporation of the solvent recrystallized in dichloromethane