Carbon Dioxide → 2,3-Dihydro-5-methyl-7-benzofurancarboxylic acid

HRID 893720Notes

Reaction equation

HRID 893720 reaction equation
Br[C:2]1[CH:7]=[C:6]([CH3:8])[CH:5]=[C:4](Br)[C:3]=1[O:10][CH2:11][CH2:12]Br.[Li]CCCC.[C:19](=[O:21])=[O:20].CC(C)=O.C(=O)=O>C1COCC1.CCCCCC>[CH3:8][C:6]1[CH:5]=[C:4]([C:19]([OH:21])=[O:20])[C:3]2[O:10][CH2:11][CH2:12][C:2]=2[CH:7]=1

Participants

7

Reactant 4

HCID 280Carbon DioxideHCID 12725189HCID 12725189, compoundHCID 18522661Acetone cardiceHCID 178418339Butyllithium2×

Product 1

HCID 148386572,3-Dihydro-5-methyl-7-benzofurancarboxylic acidYield 90.7%

Reagents, catalysts & solvents 2

HCID 8028TetrahydrofuranSolventHCID 8058HexaneSolvent

Procedure

To a stirred solution of 2-(2,6-dibromo-4-methylphenyloxy)ethyl bromide (19) (5.82 g, 15.6 mmol) in dry THF (90 ml) and hexane (30 ml) under argon there was added 7.8 ml of n-BuLi (2.5 M in hexane) at -78° C. (dry ice/acetone bath). After 30 minutes at -78° C., an additional 7.8 ml of n-BuLi was added. After an additional 1 hour stirring, the light yellow reaction solution was poured into a slurry of dry ice (prewashed with dry ether). After the mixture had come to room temperature, the precipitated white solid was collected on a filter, treated with lN HCl to adjust the pH of the supernatant liquid to 1. The mixture was cooled briefly in the freezer, and the solid collected on a filter to afford 2.52 g (90.7%) of acid 20. The crude product was recrystallized from CH3OH/H2O to yield 1.70 g (61.2%) of 20 as a white solid, mp 177-°- 79° C. IR(KBr) 3420 (OH) and 1680(C=0) cm-1NMR(CDCl3) δ 8.47 (br s, 1H, OH), 7.50 (s, 1H, aromatic proton), 7.15 (s, 1H, aromatic proton), 4.70 (t, 2H, J=9 Hz, OCH2), 3.20 (t, 2H, OCH2CH2), and 2.32 (s, 3H, CH3).

Workup

  1. customhad come to room temperature
  2. customthe precipitated white solid was collected on a filter
  3. additiontreated with lN HCl
  4. temperatureThe mixture was cooled briefly in the freezer
  5. customthe solid collected on
  6. filtrationa filter

Sources & evidence

ORD record
ord-b16d9e7541554df18e82b80959c3e862
Source dataset
uspto-grants-1992_06
Patent number
US05126364

Reaction notes

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