Hydrochloric Acid → 7-Bromo-2-methyl-1H-indene

To a solution of 116 g (0.52 mol) of 4-bromo-6-chloro-2-methyl-1-indanone in 950 ml of THF-methanol (2:1, vol.) 38.3 g (1.02 mol) of NaBH4 were added in small portions for 2 hours at −5° C. (Caution: temperature must be lower than 0° C.). The mixture was stirred overnight at ambient temperature. The resulting mixture was poured over 1000 cm3 of ice and acidified with 10% HCl to pH=4. The organic layer was separated; the aqueous layer was extracted with 3×300 ml of methyl-tert-butyl ether. The combined organic fractions were dried over K2CO3 and evaporated to dryness. To the residue 1500 ml of toluene were added. This toluene solution was treated with a catalytic amount of pTolSO3H (ca. 2 g) for 2 hours at reflux. Then this mixture was cooled to room temperature and passed through a short Silica Gel 60 column (40-63 μm, d 60 mm, 140 mm). This column was additionally eluted with 250 ml of toluene. The chromatographed product was evaporated to dryness. Fractional distillation gave the title indene, b.p. 104-108° C./5 mm Hg. Yield 100 g (93%) of colorless solid.

1. customThe organic layer was separated
2. extractionthe aqueous layer was extracted with 3×300 ml of methyl-tert-butyl ether
3. dry with materialThe combined organic fractions were dried over K2CO3
4. customevaporated to dryness
5. additionTo the residue 1500 ml of toluene were added
6. additionThis toluene solution was treated with a catalytic amount of pTolSO3H (ca. 2 g) for 2 hours
7. temperatureat reflux
8. temperatureThen this mixture was cooled to room temperature
9. washThis column was additionally eluted with 250 ml of toluene
10. customThe chromatographed product was evaporated to dryness
11. distillationFractional distillation

ORD record

ord-86e0b8e3fc2542a49ef46992dae5d29e

Source dataset

uspto-grants-2011_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07910783B2