Potassium Carbonate → 5-(4-Methoxy-2-methyl-phenyl)-4-methyl-thiophene-2-carboxylic acid methyl ester

HRID 250225Notes

Reaction equation

[CH3:1][O:2][C:3]1[CH:8]=[CH:7][C:6](B(O)O)=[C:5]([CH3:12])[CH:4]=1.[CH3:13][O:14][C:15]([C:17]1[S:18][C:19](Br)=[C:20]([CH3:22])[CH:21]=1)=[O:16].C([O-])([O-])=O.[K+].[K+]>C1(C)C=CC=CC=1.O.[Pd].C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1>[CH3:13][O:14][C:15]([C:17]1[S:18][C:19]([C:6]2[CH:7]=[CH:8][C:3]([O:2][CH3:1])=[CH:4][C:5]=2[CH3:12])=[C:20]([CH3:22])[CH:21]=1)=[O:16]

Participants

Conditions

Temperature: 80 °C

Procedure

To a mixture of 4-methoxy-2-methylphenylboronic acid (912 mg, 6 mmol), 5-bromo-4-methyl-thiophene-2-carboxylic acid methyl ester (1.1 g, 5 mmol) and K2CO3 (1.38 g, 10 mmol) in toluene (30 mL) and water (5 mL) is bubbled N2 for 15 minutes followed by addition of tetrakis(triphenylphosphine) palladium (289 mg, 0.25 mmol). The mixture is stirred at 80° C. under N2 overnight and filtered through a pad of diatomaceous earth eluting with EtOAc. The combined filtrate is concentrated. The resulting residue is purified by column chromatography (0-15% EtOAc in hexanes) to give 5-(4-methoxy-2-methyl-phenyl)-4-methyl-thiophene-2-carboxylic acid methyl ester (540 mg, 39%). 1H-NMR (CDCl3): δ 7.63 (s, 1H), 7.15 (d, 1H, J=8.4 Hz), 6.82 (d, 1H, J=2.8 Hz), 6.78 (dd, 1H, J=2.8, J=8.4 Hz), 4.79 (bs, 1H), 3.88 (s, 3H), 3.83 (s, 3H), 2.17 (s, 3H), 2.02 (s, 3H).

Workup

customis bubbled N2 for 15 minutes
filtrationfiltered through a pad of diatomaceous earth
washeluting with EtOAc
concentrationThe combined filtrate is concentrated
customThe resulting residue is purified by column chromatography (0-15% EtOAc in hexanes)

Sources & evidence

ORD record: ord-23ba90a4006f485196043be300e18797
Source dataset: uspto-grants-2011_01
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US07863302B2

Reaction notes

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