6-Methylchromone-2-carboxylic Acid → 6-methyl-3,4-dihydro-2H-1-benzopyran-2-carboxylic acid

HRID 1803758Notes

Reaction equation

[CH3:1][C:2]1[CH:3]=[C:4]2[C:9](=[CH:10][CH:11]=1)[O:8][C:7]([C:12]([OH:14])=[O:13])=[CH:6][C:5]2=O>[Pd].C(O)(=O)C>[CH3:1][C:2]1[CH:3]=[C:4]2[C:9](=[CH:10][CH:11]=1)[O:8][CH:7]([C:12]([OH:14])=[O:13])[CH2:6][CH2:5]2

Participants

Conditions

Temperature: 70 °C

Procedure

6-Methyl-4-oxo-4H-chromene-2-carboxylic acid (Aldrich, 3.5 g, 17.1 mmol) was added to a mixture of acetic acid (50 mL) and 10% palladium on carbon (0.35 g) in a Parr shaker. The glass reactor was sealed and flushed with nitrogen, and pressurized with hydrogen (60 psi). The mixture was shaken at 70° C. for 2.5 hours, and filtered and solids were rinsed with methanol. The filtrate was concentrated under reduced pressure to afford the title compound. 1H NMR (300 MHz, CDCl3) δ ppm 2.09-2.23 (m, 1H), 2.25 (s, 3H), 2.28-2.40 (m, 1H), 2.72-2.86 (m, 2H), 4.71 (dd, J=8.48, 3.39 Hz, 1H), 6.83 (t, J=8.65 Hz, 2H), 6.90-6.96 (m, 1H). MS (ESI) m/z 210.1 (M+NH4)+.

Workup

customThe glass reactor was sealed
customflushed with nitrogen
filtrationfiltered
washsolids were rinsed with methanol
concentrationThe filtrate was concentrated under reduced pressure

Sources & evidence

ORD record: ord-fd0c5f6999664da69499e1ad9c521ee3
Source dataset: uspto-grants-2013_01
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08350083B2

Reaction notes

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