Hydrochloric Acid → 9-Bromo-2-methyl-5,6,7,8-tetrahydro-1H-cyclopenta[b]naphthalene

Participants

Reaction Conditions

Reaction Steps

To a solution of 18.2 g (65.3 mmol) of 4-bromo-2-methyl-2,3,5,6,7,8-hexahydro-1H-cyclopenta[b]naphthalen-1-one in 100 ml of THF-methanol (2:1, vol.), 3.47 g (91.3 mmol) of NaBH4 was added, while vigorously stirring, over 1 h at 0° C. This mixture was stirred overnight at room temperature and then added to 300 ml of cold water and acidified with 1 M HCl to pH 1. The organic layer was separated, and the aqueous layer was extracted with 2×100 ml of methyl-tert-butyl ether. The combined extract was dried over K2CO3 and evaporated to dryness, and 300 ml of toluene was added to the yellowish oil obtained. This toluene solution was treated with a catalytic amount of pTolSO3H (ca. 0.5 g) for 15 h at reflux, cooled to room temperature, and evaporated to dryness. The crude product was purified using flash chromatography on Silica Gel 60 (40-63 μm, d 70 mm, l 150 mm; eluent: hexanes). Yield 14.1 g (82%) of white crystalline solid.

Provenance & Evidence