Acetic Acid → 7-methoxy-3,4-dihydro-2H-1-benzopyran-4-carboxylic acid

HRID 1021479Notes

Reaction equation

HRID 1021479 reaction equation
[CH3:1][O:2][C:3]1[CH:12]=[C:11]2[C:6](C(O[Si](C)(C)C)(C#N)[CH2:8][CH2:9][O:10]2)=[CH:5][CH:4]=1.[C:20]([OH:23])(=[O:22])[CH3:21]>Cl.ClCCl>[CH3:1][O:2][C:3]1[CH:12]=[C:11]2[C:6]([CH:21]([C:20]([OH:23])=[O:22])[CH2:8][CH2:9][O:10]2)=[CH:5][CH:4]=1

Participants

5

Reactant 2

HCID 176Acetic AcidHCID 670805827-Methoxy-4-(trimethylsilyloxy)chroman-4-carbonitrile

Product 1

HCID 127907997-methoxy-3,4-dihydro-2H-1-benzopyran-4-carboxylic acidYield 78.1%

Reagents, catalysts & solvents 2

HCID 313Hydrochloric AcidSolventHCID 6344DichloromethaneSolvent

Conditions

Temperature
130 °C

Procedure

To 7-methoxy-4-(trimethylsilyloxy)-3,4-dihydro-2H-chromene-4-carbonitrile (1.62 g, 5.84 mmol) in acetic acid (15 mL) and HCl (15 mL) was added SnCl2 dihydrate (5.27 g, 23.4 mmol). The reaction was heated at 130° C. for 1 day. The reaction was cooled, diluted with dichloromethane (50 mL) and washed with water (50 mL) and brine (50 mL). The combined organic layers were dried over magnesium sulfate and concentrated. The residue was chromatographed over silica gel using a gradient of 0.5% MeOH/CH2Cl2 containing 0.5% acetic acid to 10% MeOH/CH2Cl2 containing 0.5% acetic acid to provide the title compound (0.95 g, 78.1% yield).

Workup

  1. temperatureThe reaction was cooled
  2. washwashed with water (50 mL) and brine (50 mL)
  3. dry with materialThe combined organic layers were dried over magnesium sulfate
  4. concentrationconcentrated
  5. customThe residue was chromatographed over silica gel using a gradient of 0.5% MeOH/CH2Cl2 containing 0.5% acetic acid to 10% MeOH/CH2Cl2 containing 0.5% acetic acid

Sources & evidence

ORD record
ord-7a7e4308e6e94d5ebe82341b93ae9604
Source dataset
uspto-grants-2014_05
Patent number
US08716498B2

Reaction notes

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