Carbon Dioxide → 5,8-Dimethyl-4-oxo-6-thiochromanecarboxylic acid

HRID 378811Notes

Reaction equation

Br[C:2]1[C:3]([CH3:17])=[C:4]2[C:12]3([O:16]CCO3)[CH2:11][CH2:10][S:9][C:5]2=[C:6]([CH3:8])[CH:7]=1.C([Li])CCC.[C:23](=[O:25])=[O:24]>O1CCCC1.CCCCCC>[CH3:17][C:3]1[C:2]([C:23]([OH:25])=[O:24])=[CH:7][C:6]([CH3:8])=[C:5]2[C:4]=1[C:12](=[O:16])[CH2:11][CH2:10][S:9]2

Participants

Conditions

Temperature: -65 °C

Procedure

46.38 g (0.15 mol) of 6-bromo-5,8-dimethylspiro[thiochromane-4,2′-[1,3]dioxolane] were dissolved in 500 ml of tetrahydrofuran and cooled to −65° C. 80 ml (0.2 mol) of 2.5 M n-butyllithium in hexane were subsequently slowly added dropwise such that the temperature did not exceed −55° C. The mixture was stirred for another 1 h, and 90 g of dry ice were then added a little at a time. The solution was subsequently allowed to warm to room temperature, 500 ml of hexane were added and the precipitate was filtered off with suction. The precipitate was taken up in 500 ml of water and made strongly acidic using conc. hydrochloric acid. The mixture was boiled under reflux for 1 h and then allowed to cool, and the precipitated product was filtered off with suction.

Workup

customdid not exceed −55° C
temperatureto warm to room temperature
filtrationthe precipitate was filtered off with suction
temperatureunder reflux for 1 h
temperatureto cool
filtrationthe precipitated product was filtered off with suction

Sources & evidence

ORD record: ord-0d2a184bed314bd3b605965c210e573a
Source dataset: uspto-grants-2001_10
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US06297196B1

Reaction notes

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