7-fluoro-3,4-dihydro-2H-chromen-4-ol

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

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

Procedure: A reaction vessel charged with 0.5 gram (0.03 mole) of 3,4-dihydro-7-fluoro-4-hydroxy-2H-1-benzopyran and 0.02 gram (catalyst) of p-toluenesulfonic acid in 50 mL of toluene was fitted with a Soxhlet extractor containing molecular sieves (3-4 angstrom). The stirred contents of the reaction vessel was heated at reflux for 90 minutes, during which time the water by-product was collected on the molecular sieves. The reaction mixture was combined with the reaction mixture of another preparation of this compound and concentrated under reduced pressure to a residue. The residue was subjected to column chromatography on silica gel, with 1:9 ethyl acetate:hexane as the eluant. The product-containing fractions were combined and concentrated under reduced pressure, yielding 0.6 gram of 7-fluoro-2H-1-benzopyran. The NMR spectrum was consistent with the proposed structure. This reaction was repeated several times. was fitted with a Soxhlet extractor containing molecular sieves (3-4 angstrom) The stirred contents of the reaction vessel was heated was collected on the molecular sieves The reaction mixture was combined with the reaction mixture of another preparation of this compound concentrated under reduced pressure to a residue concentrated under reduced pressure

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

Procedure: To a stirred solution of 5.0 grams (0.03 mole) of 3,4-dihydro-7-fluoro-2H-1-benzopyran-4-one in 100 mL of methanol was added portionwise 3.4 grams (0.09 mole) of sodium borohydride during a one hour period, after which the reaction mixture was stirred for about 18 hours. The reaction mixture was then concentrated under reduced pressure to a residue, which was slurried in water and extracted with methylene chloride. The extract was dried with magnesium sulfate and filtered. The filtrate was concentrated under reduced pressure to a residue, which was subjected to column chromatography on silica gel, with 1:4 ethyl acetate:hexane as the eluant. The product-containing fractions were combined and concentrated under reduce pressure, yielding 4.4 grams of 3,4-dihydro-7-fluoro-4-hydroxy-2H-1-benzopyran. The NMR spectrum was consistent with the proposed structure. This reaction was repeated several times. The reaction mixture was then concentrated under reduced pressure to a residue, which extracted with methylene chloride The extract was dried with magnesium sulfate filtered The filtrate was concentrated under reduced pressure to a residue, which concentrated

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

Procedure: Schema 5 illustrates the synthesis of an amino substituted 3,4-dihydro-2H-1-benzopyran, for example, 8-amino-5-chloro-3,4-dihydro-7-fluoro-2H-1-benzopyran, starting with the reaction of an appropriately halo-substituted phenol with 3-bromopropanol under basic conditions in acetone, yielding the corresponding substituted phenoxypropanol (XI). The propanol is oxidized with Jones reagent in water and acetone, giving an acid, for example, 3-(3-fluorophenoxy)propanecarboxylic acid (XII). The acid is in turn cyclized with phosphorous pentachloride and aluminium chloride in methylene chloride, affording the corresponding 3,4-dihydro-7-substituted-2H-1-benzopyran-4-one (XIII), which is then treated with sodium borohydride in methanol, yielding the appropriate 3,4-dihydro-7-substituted-4-hydroxy-2H-1-benzopyran, for example, 3,4-dihydro-7-fluoro-4-hydroxy-2H-1-benzopyran (XIV). The 4-hydroxybenzopyran is dehydrated with molecular sieves in the present of p-toluenesulfonic acid, yielding the corresponding 7-fluoro-2H-1-benzopyran (XV). This compound is then hydrogenated in the presence of 5% palladium on carbon in ethanol, yielding 3,4-dihydro-7-fluoro-2H-1 -benzopyran (XVI), which is in turn treated with n-butyllithium and carbon dioxide at -78° C. in tetrahydrofuran, affording the corresponding 3,4-dihydro-7-fluoro-2H-1-benzopyran-8-ylcarboxylic acid (XVII). The so-prepared acid is then refluxed with diphenylphosphoryl azide under mild basic conditions in t-butanol, giving the corresponding 1,1-dimethylethyl N-(3,4-dihydro-7-fluoro-2H-1-benzopyran-8-yl)carbamate (XVIII). The carbamate is then converted to the free amine by treating it with trifluoroacetic acid, yielding the 8-amino-3,4-dihydro-7-fluoro-2H-1-benzopyran intermediate (XIX). The intermediate benzopyran is optionally halogenated in the 5-position by treatment with, for example, N-chlorosuccinimide in N,N-dimethylformamide, yielding the desired 8-amino-5-chloro-3,4-dihydro-7-fluoro-2H-1-benzopyran (XX) intermediate. Examples 11 and 12 provide detailed descriptions of how these compounds are prepared.

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

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

Procedure: To a solution of 7-fluorochroman-4-ol (1.80 g, 10.7 mmol, STEP 1) and pyridine (0.35 mL) in diethyl ether (14 mL) was added thionyl chloride (3.9 mL, 53.5 mmol) at 0° C. The reaction mixture was stirred at the same temperature for 3 hours, and evaporated to remove excess thionyl chloride. The residue was quenched with water, and extracted with ethyl acetate. The extract was washed with brine, dried over magnesium sulfate, and concentrated in vacuum to afford the title compound as a pale brown solid (2.0 g, quant.): evaporated to remove excess thionyl chloride The residue was quenched with water extracted with ethyl acetate The extract was washed with brine dried over magnesium sulfate concentrated in vacuum

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

Procedure: To a solution of 7-fluoro-2,3-dihydro-4H-chromen-4-one (6.25 g, 37.6 mmol, US 20050038032) in methanol (60 mL) was added sodium borohydride (1.57 g, 41.4 mmol) at 0° C. The reaction mixture was stirred at the same temperature for 1 hour, and evaporated to remove methanol. The residue was quenched with water, and extracted with ethyl acetate. The extract was washed with brine, dried over magnesium sulfate, and concentrated in vacuum. The residue was purified by column chromatography on silica gel (hexane:ethyl acetate=3:1 as an eluent) to afford the title compound as a pale gray solid (4.70 g, 74%): evaporated to remove methanol The residue was quenched with water extracted with ethyl acetate The extract was washed with brine dried over magnesium sulfate concentrated in vacuum The residue was purified by column chromatography on silica gel (hexane

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

Procedure: A reaction vessel charged with 0.5 gram (0.03 mole) of 3,4-dihydro-7-fluoro-4-hydroxy-2H-1-benzopyran and 0.02 gram (catalyst) of p-toluenesulfonic acid in 50 mL of toluene was fitted with a Soxhlet extractor containing molecular sieves (3-4 angstrom). The stirred contents of the reaction vessel was heated at reflux for 90 minutes, during which time the water by-product was collected on the molecular sieves. The reaction mixture was combined with the reaction mixture of another preparation of this compound and concentrated under reduced pressure to a residue. The residue was subjected to column chromatography on silica gel, with 1:9 ethyl acetate:hexane as the eluant. The product-containing fractions were combined and concentrated under reduced pressure, yielding 0.6 gram of 7-fluoro-2H-1-benzopyran. The NMR spectrum was consistent with the proposed structure. This reaction was repeated several times. was fitted with a Soxhlet extractor containing molecular sieves (3-4 angstrom) The stirred contents of the reaction vessel was heated was collected on the molecular sieves The reaction mixture was combined with the reaction mixture of another preparation of this compound concentrated under reduced pressure to a residue concentrated under reduced pressure

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

Procedure: To a stirred solution of 5.0 grams (0.03 mole) of 3,4-dihydro-7-fluoro-2H-1-benzopyran-4-one in 100 mL of methanol was added portionwise 3.4 grams (0.09 mole) of sodium borohydride during a one hour period, after which the reaction mixture was stirred for about 18 hours. The reaction mixture was then concentrated under reduced pressure to a residue, which was slurried in water and extracted with methylene chloride. The extract was dried with magnesium sulfate and filtered. The filtrate was concentrated under reduced pressure to a residue, which was subjected to column chromatography on silica gel, with 1:4 ethyl acetate:hexane as the eluant. The product-containing fractions were combined and concentrated under reduce pressure, yielding 4.4 grams of 3,4-dihydro-7-fluoro-4-hydroxy-2H-1-benzopyran. The NMR spectrum was consistent with the proposed structure. This reaction was repeated several times. The reaction mixture was then concentrated under reduced pressure to a residue, which extracted with methylene chloride The extract was dried with magnesium sulfate filtered The filtrate was concentrated under reduced pressure to a residue, which concentrated

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

Procedure: Schema 5 illustrates the synthesis of an amino substituted 3,4-dihydro-2H-1-benzopyran, for example, 8-amino-5-chloro-3,4-dihydro-7-fluoro-2H-1-benzopyran, starting with the reaction of an appropriately halo-substituted phenol with 3-bromopropanol under basic conditions in acetone, yielding the corresponding substituted phenoxypropanol (XI). The propanol is oxidized with Jones reagent in water and acetone, giving an acid, for example, 3-(3-fluorophenoxy)propanecarboxylic acid (XII). The acid is in turn cyclized with phosphorous pentachloride and aluminium chloride in methylene chloride, affording the corresponding 3,4-dihydro-7-substituted-2H-1-benzopyran-4-one (XIII), which is then treated with sodium borohydride in methanol, yielding the appropriate 3,4-dihydro-7-substituted-4-hydroxy-2H-1-benzopyran, for example, 3,4-dihydro-7-fluoro-4-hydroxy-2H-1-benzopyran (XIV). The 4-hydroxybenzopyran is dehydrated with molecular sieves in the present of p-toluenesulfonic acid, yielding the corresponding 7-fluoro-2H-1-benzopyran (XV). This compound is then hydrogenated in the presence of 5% palladium on carbon in ethanol, yielding 3,4-dihydro-7-fluoro-2H-1 -benzopyran (XVI), which is in turn treated with n-butyllithium and carbon dioxide at -78° C. in tetrahydrofuran, affording the corresponding 3,4-dihydro-7-fluoro-2H-1-benzopyran-8-ylcarboxylic acid (XVII). The so-prepared acid is then refluxed with diphenylphosphoryl azide under mild basic conditions in t-butanol, giving the corresponding 1,1-dimethylethyl N-(3,4-dihydro-7-fluoro-2H-1-benzopyran-8-yl)carbamate (XVIII). The carbamate is then converted to the free amine by treating it with trifluoroacetic acid, yielding the 8-amino-3,4-dihydro-7-fluoro-2H-1-benzopyran intermediate (XIX). The intermediate benzopyran is optionally halogenated in the 5-position by treatment with, for example, N-chlorosuccinimide in N,N-dimethylformamide, yielding the desired 8-amino-5-chloro-3,4-dihydro-7-fluoro-2H-1-benzopyran (XX) intermediate. Examples 11 and 12 provide detailed descriptions of how these compounds are prepared.