Hydrochloric Acid → 2,2-dimethyl-3,4-dihydro-2H-1-benzopyran-7-ol

HRID 1427839Notes

Reaction equation

[OH:1][C:2]1[CH:11]=[C:10]2[C:5]([C:6](=O)[CH2:7][C:8]([CH3:13])([CH3:12])[O:9]2)=[CH:4][CH:3]=1.Cl>CO.[Zn]>[CH3:12][C:8]1([CH3:13])[CH2:7][CH2:6][C:5]2[C:10](=[CH:11][C:2]([OH:1])=[CH:3][CH:4]=2)[O:9]1

Participants

Conditions

Temperature: 0 °C

Procedure

A mixture of 7-hydroxy-2,2-dimethylchroman-4-one (500 mg, 2.60 mmol) and HCl (conc. 10 mL) in MeOH (30 mL) was stirred at 0° C. for 10 min, then zinc power (300 mg) was added slowly. After stirring at room temperature for 16 hrs, the solvents were removed under reduced pressure and the mixture was extracted with EtOAc (150×3 mL). The combined organic layers were washed with brine, dried over Na2SO4, filtered and concentrated. The residue was purified by reverse phase column flash (28%-35% MeCN in 0.5% NH4HCO3) to give target product of 2,2-dimethylchroman-7-ol (290 mg, 62%) as a brown yellow solid. LCMS (ESI) m/z: 177.1 [M−H]+; 1H-NMR (500 MHz, CDCl3): δ 6.89 (d, J=8.0 Hz, 1H), 6.34 (dd, J=8.5, 2.5 Hz, 1H), 6.27 (d, J=2.5 Hz, 1H), 4.70 (s, 1H), 2.69 (t, J=13.5, 7.0 Hz, 2H), 1.77 (t, J=13.5, 7.0 Hz, 2H), 1.32 (s, 6H).

Workup

stirringAfter stirring at room temperature for 16 hrs
customthe solvents were removed under reduced pressure
extractionthe mixture was extracted with EtOAc (150×3 mL)
washThe combined organic layers were washed with brine
dry with materialdried over Na2SO4
filtrationfiltered
concentrationconcentrated
customThe residue was purified by reverse phase column flash (28%-35% MeCN in 0.5% NH4HCO3)

Sources & evidence

ORD record: ord-d9fc11a0594140398409073dc59cbdca
Source dataset: uspto-grants-2015_01
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08933236B2

Reaction notes

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