Bromocyclopentane → Methyl 6-bromo-1-cyclopentyl-1H-indazole-4-carboxylate

HRID 1501658Notes

Reaction equation

[Br:1][C:2]1[CH:3]=[C:4]([C:11]([O:13][CH3:14])=[O:12])[C:5]2[CH:6]=[N:7][NH:8][C:9]=2[CH:10]=1.C(=O)([O-])[O-].[Cs+].[Cs+].Br[CH:22]1[CH2:26][CH2:25][CH2:24][CH2:23]1>C(#N)C>[Br:1][C:2]1[CH:3]=[C:4]([C:11]([O:13][CH3:14])=[O:12])[C:5]2[CH:6]=[N:7][N:8]([CH:22]3[CH2:26][CH2:25][CH2:24][CH2:23]3)[C:9]=2[CH:10]=1

Participants

Conditions

Temperature: 90 °C

Procedure

To a stirred solution of methyl 6-bromo-1H-indazole-4-carboxylate (10 g, 39.3 mmol) in acetonitrile (100 mL), was added cesium carbonate (19.2 g, 59.05 mmol) followed by bromocyclopentane (11.93 g, 78.3 mmol). The reaction mass was stirred at 90° C. for 3-4 h. On completion of reaction, acetonitrile was removed under reduced pressure and water added. Extraction was carried out using ethyl acetate and the combined organic layers were washed with water, brine and dried over anhydrous Na2SO4. The solvent was removed under reduced pressure and the residue purified by silica gel column chromatography to obtain methyl 6-bromo-1-cyclopentyl-1H-indazole-4-carboxylate (3.7 g, 29.2%). The regiochemistry of the cyclopentyl group was confirmed by a NOE experiment.

Workup

customwas removed under reduced pressure and water
additionadded
extractionExtraction
washthe combined organic layers were washed with water, brine
dry with materialdried over anhydrous Na2SO4
customThe solvent was removed under reduced pressure
customthe residue purified by silica gel column chromatography

Sources & evidence

ORD record: ord-df947d45b4f04edc960d5d2c70e690a3
Source dataset: uspto-grants-2015_12
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US09206157B2

Reaction notes

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