Carbon Dioxide → 4,4-Dimethyl-3,4-dihydro-2H-1-benzothiopyran-6-carboxylic acid

HRID 2050980Notes

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]1

Participants

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 1.7M (0.048 mmol) tertbutyllithium 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-5fde764441854b05a4abe694d8060279
Source dataset: uspto-grants-1991_05
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US05015658

Reaction notes

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