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

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:

Conditions: temp:80.01; pressure:0.00; stir:

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

Procedure: Borane-dimethylsulfide complex (BH3—SMe2) (10 M, 1.14 mL, 11.4 mmol) in THF was added dropwise at 0° C. to a solution of compound 1 (1 g, 2.9 mmol) in THF (12 mL), and the resultant mixture was stirred at 0° C. for 4 hrs. After completion of the reaction, the mixture was quenched with H2O (7 mL), and then continually stirred for 5 min, followed by addition of 10% NaOH (2 mL) and 37% H2O2 (0.36 mL). After stirring for 30 min, the mixture was extracted with CH2Cl2 (30 mL×5). The organic layers were combined and dried with anhydrous MgSO4. After filtration, the filtrate was concentrated in vacuo, followed by purification via silica gel column chromatography (ethyl acetate/n-hexane=1:4), thus giving the title compound 4 as a colorless crystal (0.63 g, 60% yield). After completion of the reaction the mixture was quenched with H2O (7 mL) followed by addition of 10% NaOH (2 mL) and 37% H2O2 (0.36 mL) After stirring for 30 min the mixture was extracted with CH2Cl2 (30 mL×5) dried with anhydrous MgSO4 After filtration the filtrate was concentrated in vacuo followed by purification via silica gel column chromatography (ethyl acetate/n-hexane=1:4)

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

Procedure: Borane-dimethylsulfide complex (BH3—SMe2) (10 M, 1.14 mL, 11.4 mmol) in THF was added dropwise at 0° C. to a solution of compound 1 (1 g, 2.9 mmol) in THF (12 mL), and the resultant mixture was stirred at 0° C. for 4 hrs. After completion of the reaction, the mixture was quenched with H2O (7 mL), and then continually stirred for 5 min, followed by addition of 10% NaOH (2 mL) and 37% H2O2 (0.36 mL). After stirring for 30 min, the mixture was extracted with CH2Cl2 (30 mL×5). The organic layers were combined and dried with anhydrous MgSO4. After filtration, the filtrate was concentrated in vacuo, followed by purification via silica gel column chromatography (ethyl acetate/n-hexane=1:4), thus giving the title compound 4 as a colorless crystal (0.63 g, 60% yield). After completion of the reaction the mixture was quenched with H2O (7 mL) followed by addition of 10% NaOH (2 mL) and 37% H2O2 (0.36 mL) After stirring for 30 min the mixture was extracted with CH2Cl2 (30 mL×5) dried with anhydrous MgSO4 After filtration the filtrate was concentrated in vacuo followed by purification via silica gel column chromatography (ethyl acetate/n-hexane=1:4)

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

Procedure: Using the general procedure of hydroboration-oxidation, compound 1 was converted into a chroman-4-ol (compound 4) at a yield of 60%. Compound 4 was treated with 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) in refluxing 1,4-dioxane to undergo oxidation-dehydrogenation to give an isoflavone (compound 5) at a yield of 78%. After the deprotection of compound 5 with AlCl3/EtSH, daidzein (compound 6a) was produced at a yield of 92%. On the other hand, compound 5 could be selectively debenzylated with Pearlman's reagent to give formononetin (compound 6b) at a yield of 94%,

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

Procedure: Using the general procedure of hydroboration-oxidation, compound 1 was converted into a chroman-4-ol (compound 4) at a yield of 60%. Compound 4 was treated with 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) in refluxing 1,4-dioxane to undergo oxidation-dehydrogenation to give an isoflavone (compound 5) at a yield of 78%. After the deprotection of compound 5 with AlCl3/EtSH, daidzein (compound 6a) was produced at a yield of 92%. On the other hand, compound 5 could be selectively debenzylated with Pearlman's reagent to give formononetin (compound 6b) at a yield of 94%,

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

Procedure: A mixture of 4-chromanol (30 g; 0.02 mole), benzene (200 ml) and 4-toluenesulfonic acid (200 mg) was refluxed, with a Dean-Stark trap, until separation of water ceased (ca. 3 hrs.). It was then washed successively with saturated NaHCO3 aqueous solution and water, dried over anhydrous MgSO4 and evaporated under reduced pressure to yield an almost colorless liquid which was distilled under vacuum to give benzopyran (20.2 g, 76.4%) b.p. 73°-78°/3 torr. (ca. 3 hrs.) It was then washed successively with saturated NaHCO3 aqueous solution and water dried over anhydrous MgSO4 evaporated under reduced pressure to yield an almost colorless liquid which was distilled under vacuum

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

Procedure: A mixture of 4-chromanol (30 g; 0.02 mole), benzene (200 ml) and 4-toluenesulfonic acid (200 mg) was refluxed, with a Dean-Stark trap, until separation of water ceased (ca. 3 hrs.). It was then washed successively with saturated NaHCO3 aqueous solution and water, dried over anhydrous MgSO4 and evaporated under reduced pressure to yield an almost colorless liquid which was distilled under vacuum to give benzopyran (20.2 g, 76.4%) b.p. 73°-78°/3 torr. (ca. 3 hrs.) It was then washed successively with saturated NaHCO3 aqueous solution and water dried over anhydrous MgSO4 evaporated under reduced pressure to yield an almost colorless liquid which was distilled under vacuum