Sodium Carbonate → Ethyl 3-methylthiophene-2-carboxylate

HRID 2269668Notes

Reaction equation

HRID 2269668 reaction equation
Br[C:2]1[S:3][CH:4]=[CH:5][C:6]=1[CH3:7].C1(P([C:31]2[CH:36]=CC=CC=2)CCCP(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.[C:37]([O-])([O-:39])=[O:38].[Na+].[Na+]>CC([O-])=O.CC([O-])=O.[Pd+2].CCO>[CH3:7][C:6]1[CH:5]=[CH:4][S:3][C:2]=1[C:37]([O:39][CH2:36][CH3:31])=[O:38]

Participants

6

Reactant 3

HCID 10340Sodium CarbonateHCID 812191,3-Bis(diphenylphosphino)propaneHCID 843142-Bromo-3-methylthiophene

Product 1

HCID 18347931Ethyl 3-methylthiophene-2-carboxylate

Reagents, catalysts & solvents 2

HCID 167845palladium(II) acetateCatalystHCID 702EthanolSolvent

Conditions

Temperature
120 °C

Procedure

2-Bromo-3-methylthiophene (Lancaster, 26.4 g, 0.149 mol), Pd(OAc)2 (0.213 g, 0.95 mmol), 1,3-bis(diphenylphosphino) propane (0.49 g, 1.2 mmol), Na2CO3 (21.1 g, 0.20 mol), and 200 mL abs EtOH were placed into a 450 mL Hastalloy-C stirred pressure reactor, purged with N2, then pressurized with 490 psig CO, and the stirring reactor was heated to 120° C. for 36 hrs. Analysis of the reaction mixture by gas chromatography showed 1.3% and 96.9% area % starting bromomethylthiophene and carbonylation product, respectively. After cooling and venting, the reactor contents were filtered and evaporated to give a light yellow oil/solid mixture. This residue was extracted with 1,2-dichloroethane and water, and the organic phase was evaporated to give an oil. Filtration of this oil to remove residual salt gave 20.7 g (81% wt. % yield) of orange oil as ethyl 3-methyl-2-thiophenecarboxylate. 13C NMR {1H} CDCl3: δ162.8, 145.9, 131.7, 129.9, 127.0, 60.6, 15.9, 14.4 ppm.

Workup

  1. custompurged with N2
  2. temperatureAfter cooling
  3. filtrationthe reactor contents were filtered
  4. customevaporated
  5. customto give a light yellow oil/solid mixture
  6. extractionThis residue was extracted with 1,2-dichloroethane and water
  7. customthe organic phase was evaporated
  8. customto give an oil
  9. filtrationFiltration of this oil
  10. customto remove residual salt

Sources & evidence

ORD record
ord-4165e9c2e6d148cab838c52c3195847b
Source dataset
uspto-grants-2001_12
Patent number
US06329528B1

Reaction notes

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