Cesium carbonate → 2-Chloro-3-phenylpyrazolo[1,5-A]pyridine

HRID 530034Notes

Reaction equation

[Cl:1][C:2]1[C:10](I)=[C:5]2[CH:6]=[CH:7][CH:8]=[CH:9][N:4]2[N:3]=1.[C:12]1(B(O)O)[CH:17]=[CH:16][CH:15]=[CH:14][CH:13]=1.C(=O)([O-])[O-].[Cs+].[Cs+].C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1>O1CCCC1.C([O-])(=O)C.[Pd+2].C([O-])(=O)C>[Cl:1][C:2]1[C:10]([C:12]2[CH:17]=[CH:16][CH:15]=[CH:14][CH:13]=2)=[C:5]2[CH:6]=[CH:7][CH:8]=[CH:9][N:4]2[N:3]=1

Participants

Conditions

Temperature: 100 °C

Procedure

A mixture 2-chloro-3-iodopyrazolo[1,5-a]pyridine (27-3; 0.8 g, 2.87 mmol), phenyl boronic acid (0.42 g, 3.44 mmol), and cesium carbonate (2.8 g, 8.61 mmol), in tetrahydrofuran (15.0 mL) was degassed for 10 min. Next, triphenylphosphine (0.15 g, 0.574 mmol) and palladium acetate (0.064 g, 0.287 mmol) were added and heated in a sealed tube at 100° C. for 18 h. The reaction mixture was then cooled to room temperature, filtered and concentrated under reduced pressure. Purification of the resulting residue by flash chromatography on silica gel (0-5% ethyl acetate in hexanes) provided 2-chloro-3-phenylpyrazolo[1,5-a]pyridine. 1H NMR (400 MHz, DMSO-d6) δ 8.70-8.68 (d, J=7.2 Hz, 1 H), 7.69-7.67 (d, J=8.8 Hz, 1 H), 7.57-7.55 (d, J=7.2 Hz, 2 H), 7.52-7.48 (t, J=7.6 Hz, 2 H), 7.39-7.34 (m, 2 H), 7.03-7.00 (m, 1 H). MS (M+1): 229.1.

Workup

temperatureThe reaction mixture was then cooled to room temperature
filtrationfiltered
concentrationconcentrated under reduced pressure
customPurification of the resulting residue by flash chromatography on silica gel (0-5% ethyl acetate in hexanes)

Sources & evidence

ORD record: ord-d672dc4479d74cceb87f9b1ce0a1455f
Source dataset: uspto-grants-2016_05
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US09351973B2

Reaction notes

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