Carbon Dioxide → 4,4-Dimethyl-3,4-dihydro-2H-1-benzothiopyran-6-carboxylic acid
Reaction equation
[CH3:1][C:2]1([CH3:13])[C:11]2[C:6](=[CH:7][CH:8]=[C:9](Br)[CH:10]=2)[S:5][CH2:4][CH2:3]1.C([Li])(C)(C)C.[C:19](=[O:21])=[O:20].O>CCOCC.CCCCC>[CH3:1][C:2]1([CH3:13])[C:11]2[C:6](=[CH:7][CH:8]=[C:9]([C:19]([OH:21])=[O:20])[CH:10]=2)[S:5][CH2:4][CH2:3]1Participants
Conditions
- Temperature
- -78 °C
Procedure
To a stirred solution of 5.14 g (0.02 mmol) of 4,4-dimethyl-6-bromothiochroman in 40 ml of dry ether at -78° C. was added dropwise 28.2 ml of 1.7 M 0.048 mmol) tert-butyllithium in pentane. The mixture was stirred at -78° C. for 2.5 hours and then treated with an excess of solid carbon dioxide. The mixture was warmed to room temperature and treated with sufficient water to dissolve the solids. The aqueous layer was then separated, acidified with dilute sulfuric acid and extracted with three portions of ether. The ether extracts were combined and washed successively with water and saturated NaCl solution and then dried (MgSO4). The solution was filtered and the solvent removed in-vacuo and the residue recrystallized from ethyl acetate and hexane to give the title compound as a white solid. PMR (CDCl3): δ1.37 (6H, s), 1.97 (2H, m), 3.08 (2H, m), 7.17 (1H, d, J~ 8.0 Hz), 7.74 (1H dd, J~8.0, 1.9 Hz), 8.11 (1H, d, J~1.9 Hz).
Workup
- temperatureThe mixture was warmed to room temperature
- dissolutionto dissolve the solids
- customThe aqueous layer was then separated
- extractionextracted with three portions of ether
- washwashed successively with water and saturated NaCl solution
- dry with materialdried (MgSO4)
- filtrationThe solution was filtered
- customthe solvent removed in-vacuo
- customthe residue recrystallized from ethyl acetate and hexane
Sources & evidence
- ORD record
- ord-f31802d79166462d9fde120fdacaf69a
- Source dataset
- uspto-grants-1990_01
- Patent number
- US04895868
Reaction notes
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