Hydrochloric Acid → HCID 57723647、化合物

To a solution of 16.9 g (52.2 mmol) of 4,7-dibromo-2,6-dimethyl-1-indanone in 300 ml of THF-methanol (2:1, vol.), 3.80 g (100 mmol) of NaBH4 was added in small portions over 1.5 hours at −5° C. (Caution: temperature must be lower 0° C.). The mixture was stirred overnight at ambient temperature. The resulting mixture was acidified with 10% HCl to pH=4. The organic layer was separated; the aqueous layer was extracted with 3×100 ml of methyl-tert-butyl ether. The combined organic fractions were dried over Na2SO4 and evaporated to dryness. To the residue 500 ml of toluene were added. This toluene solution was treated with pTolSO3H (ca. 5 g) for 2 hours at reflux. Then, one more portion (ca. 5 g) of pTolSO3H was added, and the mixture was refluxed for an additional 2 hours. The resulting mixture was cooled to room temperature and passed through a short Silica Gel 60 column (40-63 μm, d 40 mm, 1 100 mm). This column was additionally eluted with 600 ml of hexanes. The combined extract was evaporated to dryness to give a white solid of the title product. Yield 13.6 g (85%).