Water → 1-Cyclopentyl-3-ethyl-1H-indazole-6-carboxylic Acid Methyl Ester

HRID 322098Notes

Reaction equation

HRID 322098 reaction equation
[H-].[Na+].[CH3:3][O:4][C:5]([C:7]1[CH:15]=[C:14]2[C:10]([C:11]([CH2:16][CH3:17])=[N:12][NH:13]2)=[CH:9][CH:8]=1)=[O:6].[CH:18]1(Br)[CH2:22][CH2:21][CH2:20][CH2:19]1.O>CN(C=O)C>[CH3:3][O:4][C:5]([C:7]1[CH:15]=[C:14]2[C:10]([C:11]([CH2:16][CH3:17])=[N:12][N:13]2[CH:18]2[CH2:22][CH2:21][CH2:20][CH2:19]2)=[CH:9][CH:8]=1)=[O:6]

Participants

6

Reactant 4

HCID 962WaterHCID 8728BromocyclopentaneHCID 24758Sodium hydrideHCID 178438014HCID 178438014, compound

Product 1

HCID 158960821-Cyclopentyl-3-ethyl-1H-indazole-6-carboxylic Acid Methyl EsterYield 72.1%

Reagents, catalysts & solvents 1

HCID 6228DimethylformamideSolvent

Procedure

1.17 g (29.4 mmol, 1.05 equiv) sodium hydride, 60% oil dispersion, was added in one portion to a room temperature solution of 5.7 g (27.9 mmol, 1.0 equiv) 3-ethyl-1H-indazole-6-carboxylic acid methyl ester in 125 mL anhydrous DMF. After 20 minutes, 3.89 mL (36.6 mmol, 1.3 equiv) cyclopentyl bromide were added dropwise, and the reaction was mixture allowed to stir overnight at room temperature. The mixture was then poured into 1 L H2O and extracted 3×450 mL ethyl acetate. The organic extracts were combined, washed 3×400 mL H2O, 1×200 mL brine, and dried over Na2SO4. Filtration, concentration of filtrate and drying gave an amber oil, which was purified on a silica gel column (10% ethyl acetate/hexanes, gravity) to give 5.48 g (72%) of a clear oil: 1H NMR (300 MHz, CDCl3) d 8.16 (d, 1H, J=1.0 Hz), 7.7 (m, 2H), 5.00 (quintet, 1H, J=7.5 Hz), 3.97 (s, 3H), 3.01 (q, 2H, J=7.6 Hz), 2.2 (m, 4H), 2.0 (m, 2H), 1.8 (m, 2H), 1.39 (t, 3H, J=7.6 Hz); HRMS calcd for C16H20N2O2; 272.1526. Found: 272.15078.

Workup

  1. extractionextracted 3×450 mL ethyl acetate
  2. washwashed 3×400 mL H2O, 1×200 mL brine
  3. dry with materialdried over Na2SO4
  4. filtrationFiltration, concentration of filtrate
  5. customdrying
  6. customgave an amber oil, which
  7. customwas purified on a silica gel column (10% ethyl acetate/hexanes, gravity)

Sources & evidence

ORD record
ord-56f040fac0214c629cc7a590e9252482
Source dataset
uspto-grants-2001_04
Patent number
US06211222B1

Reaction notes

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