methyl 9H-xanthene-9-carboxylate

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

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

Procedure: 16.8 g (0.07 mol) of methyl 9-xanthenecarboxylate (obtainable according to step 1.1.a) are dissolved in 300 mL of tetrahydrofuran and 9.1 g (0.077 mol) of potassium tert-butoxide are added batchwise while cooling. Then difluorochloromethane is piped in at 0° C. over a period of 1.5 hours. After all the gas has been piped in, the reaction mixture is left to stand for 72 hours at ambient temperature. The reaction mixture is then diluted with water to a total volume of about 2000 mL, extracted with ethyl acetate, the organic phase is separated off and washed with 5% aqueous sodium carbonate solution. After being extracted again with water, the organic phase is dried over magnesium sulfate and the solvent is removed by distillation. The crude product is purified by chromatography on silica gel (eluent: cyclohexane-ethyl acetate (98:2)) or by recrystallization from cyclohexane. Yield: 5.35 g of white crystals (26% of theoretical yield); melting point: 101° C. while cooling is left extracted with ethyl acetate the organic phase is separated off washed with 5% aqueous sodium carbonate solution After being extracted again with water the organic phase is dried over magnesium sulfate the solvent is removed by distillation The crude product is purified by chromatography on silica gel (eluent: cyclohexane-ethyl acetate (98:2)) or by recrystallization from cyclohexane

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

Procedure: 16.8 g (0.07 mol) of methyl 9-xanthenecarboxylate (obtainable according to step 1.1.a) are dissolved in 300 mL of tetrahydrofuran and 9.1 g (0.077 mol) of potassium tert-butoxide are added batchwise while cooling. Then difluorochloromethane is piped in at 0° C. over a period of 1.5 hours. After all the gas has been piped in, the reaction mixture is left to stand for 72 hours at ambient temperature. The reaction mixture is then diluted with water to a total volume of about 2000 mL, extracted with ethyl acetate, the organic phase is separated off and washed with 5% aqueous sodium carbonate solution. After being extracted again with water, the organic phase is dried over magnesium sulfate and the solvent is removed by distillation. The crude product is purified by chromatography on silica gel (eluent: cyclohexane-ethyl acetate (98:2)) or by recrystallization from cyclohexane. Yield: 5.35 g of white crystals (26% of theoretical yield); melting point: 101° C. while cooling is left extracted with ethyl acetate the organic phase is separated off washed with 5% aqueous sodium carbonate solution After being extracted again with water the organic phase is dried over magnesium sulfate the solvent is removed by distillation The crude product is purified by chromatography on silica gel (eluent: cyclohexane-ethyl acetate (98:2)) or by recrystallization from cyclohexane

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

Procedure: 10.0 g (0.042 mol) of methyl 9-xanthenecarboxylate (obtainable according to step 1.1.a) are dissolved in 100 mL of tetrahydrofuran and combined batchwise with 5.16 g (0.044 mol) of potassium tert-butoxide while cooling. Then at about 18° C. to 22° C., 6.296 mL (0.083 mol) of bromoethane are added dropwise; after it has all been added, the mixture is stirred for about 1.5 hours at ambient temperature. The precipitate formed is suction filtered and the solvent is removed by distillation. The residue remaining is taken up in diethyl ether and extracted with water. The organic phase is dried over magnesium sulfate and the solvent is removed by distillation. The crude product obtained is used in the next step without any further purification. Yield: 7.92 g of yellow oil (70% of theoretical yield). while cooling all been added The precipitate formed filtered the solvent is removed by distillation extracted with water The organic phase is dried over magnesium sulfate the solvent is removed by distillation

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

Procedure: 9.61 g (0.04 mol) of methyl 9-xanthenecarboxylate (obtainable according to step 1.1.a) are dissolved in 150 mL of tetrahydrofuran, combined with a solution of 5.0 g (0.042 mol) potassium lert-butoxide in THF, and stirred for 10 minutes. 5 mL (0.08 mol) of methyl iodide are then added dropwise with gentle cooling; after all has been added, the mixture is stirred for 1 hour at ambient temperature. The reaction mixture is diluted with water to a total volume of 800 mL, extracted with diethyl ether, and the organic phase is extracted with saturated, aqueous Na2CO3 solution, washed with water, dried over magnesium sulfate, and the solvent is distilled off. The product is purified by recrystallization from methanol. Yield: 6.05 g of white crystals (70% of theoretical yield); melting point: 91° C.-92° C. after all has been added the mixture is stirred for 1 hour at ambient temperature extracted with diethyl ether the organic phase is extracted with saturated, aqueous Na2CO3 solution washed with water dried over magnesium sulfate the solvent is distilled off The product is purified by recrystallization from methanol

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

Procedure: 9.61 g (0.04 mol) of methyl 9-xanthenecarboxylate (obtainable according to step 1.1.a) are dissolved in 150 mL of tetrahydrofuran, combined with a solution of 5.0 g (0.042 mol) potassium lert-butoxide in THF, and stirred for 10 minutes. 5 mL (0.08 mol) of methyl iodide are then added dropwise with gentle cooling; after all has been added, the mixture is stirred for 1 hour at ambient temperature. The reaction mixture is diluted with water to a total volume of 800 mL, extracted with diethyl ether, and the organic phase is extracted with saturated, aqueous Na2CO3 solution, washed with water, dried over magnesium sulfate, and the solvent is distilled off. The product is purified by recrystallization from methanol. Yield: 6.05 g of white crystals (70% of theoretical yield); melting point: 91° C.-92° C. after all has been added the mixture is stirred for 1 hour at ambient temperature extracted with diethyl ether the organic phase is extracted with saturated, aqueous Na2CO3 solution washed with water dried over magnesium sulfate the solvent is distilled off The product is purified by recrystallization from methanol

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

Procedure: 48.05 g (0.2 mol) methyl xanthene-9-carboxylate are dissolved in 1200 mL of tetrahydrofuran and at 0° C. combined with 23.63 g (0.2 mol) of potassium tert-butoxide. Oxygen is the piped in for 2 hours at −10° C. to −5° C., then the mixture is acidified with 2 N aqueous hydrochloric acid and the majority of the solvent is distilled off. The residue remaining is extracted with ethyl acetate and water, the organic phase is extracted with aqueous Na2S2O5 solution, washed with water, and dried, and the solvent is distilled off. The product is purified by crystallization from diisopropylether and cyclohexane. Yield: 11.10 g white crystals (22% of theoretical yield) in for 2 hours at −10° C. to −5° C. the majority of the solvent is distilled off The residue remaining is extracted with ethyl acetate and water the organic phase is extracted with aqueous Na2S2O5 solution washed with water dried the solvent is distilled off The product is purified by crystallization from diisopropylether and cyclohexane

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

Procedure: 48.05 g (0.2 mol) methyl xanthene-9-carboxylate are dissolved in 1200 mL of tetrahydrofuran and at 0° C. combined with 23.63 g (0.2 mol) of potassium tert-butoxide. Oxygen is the piped in for 2 hours at −10° C. to −5° C., then the mixture is acidified with 2 N aqueous hydrochloric acid and the majority of the solvent is distilled off. The residue remaining is extracted with ethyl acetate and water, the organic phase is extracted with aqueous Na2S2O5 solution, washed with water, and dried, and the solvent is distilled off. The product is purified by crystallization from diisopropylether and cyclohexane. Yield: 11.10 g white crystals (22% of theoretical yield) in for 2 hours at −10° C. to −5° C. the majority of the solvent is distilled off The residue remaining is extracted with ethyl acetate and water the organic phase is extracted with aqueous Na2S2O5 solution washed with water dried the solvent is distilled off The product is purified by crystallization from diisopropylether and cyclohexane

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

Procedure: A sodium ethoxide solution is prepared from 21.75 g (0.95 mol) of sodium and 1500 mL of ethanol. 214 g (0.95 mol) of xanthene-9-carboxylic acid is added batchwise to this solution and the suspension obtained is stirred for 1 hour at ambient temperature. Then the solid is separated off, washed with 1500 mL diethyl ether, and the isolated crystals are suspended in 1500 mL of dimethylformamide and combined with 126.73 mL (2.0 mol) of methyl iodide with stirring. The solution formed is left to stand for 24 hours at ambient temperature, then diluted with water to a total volume of 6 L, crystallized, suction filtered, washed with water, and dried. Yield: 167 g of white crystals (74% of theoretical yield); melting point: 82° C. the suspension obtained Then the solid is separated off washed with 1500 mL diethyl ether with stirring The solution formed is left to stand for 24 hours at ambient temperature crystallized suction filtered washed with water dried

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

Procedure: 3.25 g (13.53 mmol) of methyl 9H-xanthene-9-carboxylate are dissolved in 70 ml THF, the solution is cooled with an ice bath and 10.15 ml (20.29 mmol) of a 2M solution of LDA are added drop wise whilst keeping the temperature at 0° C. After stirring at room temperature for 1 hr, 1.68 ml (27.06 mmol) of iodomethane are added drop wise and the system is stirred at rt overnight. The solution is poured over excess of saturated solution of ammonium chloride and is extracted thrice with ethyl ether. After washing with brine, the solution is dried and concentrated to give a reddish residue which is purified by column chromatography (Cl3CH/hexane from 1:3 to 1:1) to give 2.6 g of the title compound (75% yield) as a white solid. the solution is cooled with an ice bath at 0° C the system is stirred at rt overnight is extracted thrice with ethyl ether After washing with brine the solution is dried concentrated to give a reddish residue which is purified by column chromatography (Cl3CH/hexane from 1:3 to 1:1)

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

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

Procedure: A sodium ethoxide solution is generated from 21.75 g (0.95 mol) of sodium and 1500 mL of ethanol. 214 g (0.95 mol) of xanthene-9-carboxylic acid is added batchwise to this solution and the resulting suspension is stirred for 1 hour at ambient temperature. Then the solid is separated off, washed with 1500 mL of diethyl ether, and the isolated crystals are suspended in 1500 mL of dimethylformamide and 126.73 mL (2.0 mol) of methyl iodide is added with stirring. The solution obtained is left to stand for 24 hours at ambient temperature, then diluted with water to a total volume of 6 L, crystallized, suction filtered, washed with water, and dried. Yield: 167 g of white crystals (74% of theoretical yield); melting point: 82° C. Then the solid is separated off washed with 1500 mL of diethyl ether with stirring The solution obtained is left to stand for 24 hours at ambient temperature crystallized suction filtered washed with water dried