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

HRID 1488577Notes

Reaction equation

[CH:1]([S:5][C:6]1[C:11]([C:12]([CH3:15])([CH3:14])[CH3:13])=[CH:10][CH:9]=[CH:8][C:7]=1Br)=[C:2]([CH3:4])[CH3:3].[PH2](O)=O.C(N(CC)CC)C.Cl>O1CCOCC1.[Cl-].[Na+].O>[CH3:3][C:2]1([CH3:4])[CH2:1][S:5][C:6]2[C:11]([C:12]([CH3:15])([CH3:14])[CH3:13])=[CH:10][CH:9]=[CH:8][C:7]1=2

Participants

Conditions

Temperature: 24 °C

Procedure

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.

Workup

customby bubbling with N2 for 20 min
temperatureThe solution is then heated under N2
temperatureto reflux
extractionThe mixture is extracted with Et2O (3×50 mL)
extractionthe ethereal layers are back extracted with 1N NaOH (40 mL)
dry with materialThe organic phase is dried (MgSO4)
filtrationfiltered
customevaporated to a yellow oil
distillationKugelrohr distillation

Sources & evidence

ORD record: ord-e06977f8af2744b9acf9f84ff78c9807
Source dataset: uspto-grants-1997_10
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US05674891

Reaction notes

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