6-bromo-2,2-dimethyl-3,4-dihydrochromene

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

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

Procedure: To a nitrogen flushed 100 mL round bottom flask were added 6-bromo-2,2-dimethyl-3,4-dihydro-2H-chromene (0.41 g, 1.7 mmol) and THF (6 mL). A solution of n-BuLi in hexanes (0.69 mL, 2.6 M, 1.79 mmol) was added at −78° C. The resulting reaction mixture was stirred at −78° C. for 10 minutes when DMF (0.20 mL, 2.55 mmol) was added. The reaction mixture was allowed to warm to room temperature and was diluted with EtOAc (25 mL). It was stirred over wet silica gel (10 g silica gel/0.5 mL water) for 10 minutes and was filtered. The solid was rinsed with EtOAc and the filtrate was concentrated. The residue was purified on a silica gel column eluting with a gradient of 100% hexanes to 20% EtOAc/hexanes to give the title intermediate (0.25 g) as a light yellow oil. To a nitrogen flushed 100 mL round bottom flask The resulting reaction mixture was added was filtered The solid was rinsed with EtOAc the filtrate was concentrated The residue was purified on a silica gel column eluting with a gradient of 100% hexanes to 20% EtOAc/hexanes

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

Procedure: To a nitrogen flushed 100 mL round bottom flask were added 6-bromo-2,2-dimethyl-3,4-dihydro-2H-chromene (0.41 g, 1.7 mmol) and THF (6 mL). A solution of n-BuLi in hexanes (0.69 mL, 2.6 M, 1.79 mmol) was added at −78° C. The resulting reaction mixture was stirred at −78° C. for 10 minutes when DMF (0.20 mL, 2.55 mmol) was added. The reaction mixture was allowed to warm to room temperature and was diluted with EtOAc (25 mL). It was stirred over wet silica gel (10 g silica gel/0.5 mL water) for 10 minutes and was filtered. The solid was rinsed with EtOAc and the filtrate was concentrated. The residue was purified on a silica gel column eluting with a gradient of 100% hexanes to 20% EtOAc/hexanes to give the title intermediate (0.25 g) as a light yellow oil. To a nitrogen flushed 100 mL round bottom flask The resulting reaction mixture was added was filtered The solid was rinsed with EtOAc the filtrate was concentrated The residue was purified on a silica gel column eluting with a gradient of 100% hexanes to 20% EtOAc/hexanes

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 6-bromo-2,2-dimethyl-2,3-dihydro-4H-1-benzopyran-4-one (7.57 g) in trifluoroacetic acid (21.4 ml) was added at room temperature triethylsilane (10.4 ml), and the mixture was stirred for 4 days. To the mixture was added triethylsilane (7.1 ml), and the mixture was stirred at 50° C. for 24 hours. To the mixture was added at 0° C. 12N sodium hydroxide solution to make the solution alkaline, and the mixture was extracted with diethylether. The organic layer was washed with saturated brine, dried with magnesium sulfate and concentrated under reduced pressure. The residue was purified with silica gel column chromatography (hexane) to give colorless oil of 6-bromo-2,2-dimethyl-3,4-dihydro-2H-1-benzopyran (10.77 g). the mixture was stirred at 50° C. for 24 hours To the mixture was added at 0° C the mixture was extracted with diethylether The organic layer was washed with saturated brine dried with magnesium sulfate concentrated under reduced pressure The residue was purified with silica gel column chromatography (hexane)

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

Procedure: To a nitrogen flushed 100 mL round bottom flask were added 6-bromo-2,2-dimethyl-3,4-dihydro-2H-chromene (0.41 g, 1.7 mmol) and THF (6 mL). A solution of n-BuLi in hexanes (0.69 mL, 2.6 M, 1.79 mmol) was added at −78° C. The resulting reaction mixture was stirred at −78° C. for 10 minutes when DMF (0.20 mL, 2.55 mmol) was added. The reaction mixture was allowed to warm to room temperature and was diluted with EtOAc (25 mL). It was stirred over wet silica gel (10 g silica gel/0.5 mL water) for 10 minutes and was filtered. The solid was rinsed with EtOAc and the filtrate was concentrated. The residue was purified on a silica gel column eluting with a gradient of 100% hexanes to 20% EtOAc/hexanes to give the title intermediate (0.25 g) as a light yellow oil. To a nitrogen flushed 100 mL round bottom flask The resulting reaction mixture was added was filtered The solid was rinsed with EtOAc the filtrate was concentrated The residue was purified on a silica gel column eluting with a gradient of 100% hexanes to 20% EtOAc/hexanes