Hydrochloric Acid → 7-tert-butyl-2,3-dihydro-3,3-dimethylbenzothiophene

Participants

Reaction Conditions

Reaction Steps

A solution of 2-bromo-6-tert-butylphenyl isobutenyl thioether (600 mg, 2.07 mmol), 90% hypophosphorous acid (4.4 g, 60 mmol), and triethylamine (8.4 mL, 60 mmol) in dioxane (30 mL) is deoxygenated by bubbling with N2 for 20 min. The solution is then heated under N2 to reflux, and a solution of azo-bis-isobutyrylnitrile (205 mg, 1.04 mmol) in deoxygenated dioxane (2 mL) is added in 0.2-mL portions over 3 h. The reaction is allowed to cool to 24° C., and 1N HCl (40 mL) and brine (30 mL) are added. The mixture is extracted with Et2O (3×50 mL), and the ethereal layers are back extracted with 1N NaOH (40 mL). The organic phase is dried (MgSO4), filtered and evaporated to a yellow oil. Kugelrohr distillation provides 3,3-dimethyl-7-tert-butyl-2,3-dihydrobenzo[b]thiophene as a colorless oil.

Provenance & Evidence