Sodium borohydride → HCID 86713795, compound

HRID 521849Notes

Reaction equation

HRID 521849 reaction equation
[CH3:1][N:2]1[C:6]([CH:7]2[O:13][CH2:12][CH2:11][C:10](=[O:14])[CH2:9][CH2:8]2)=[C:5]([N+:15]([O-:17])=[O:16])[CH:4]=[N:3]1.[BH4-].[Na+]>CO>[CH3:1][N:2]1[C:6]([CH:7]2[O:13][CH2:12][CH2:11][CH:10]([OH:14])[CH2:9][CH2:8]2)=[C:5]([N+:15]([O-:17])=[O:16])[CH:4]=[N:3]1

Participants

4

Reactant 2

HCID 4311764Sodium borohydrideHCID 86713792HCID 86713792, compound

Product 1

HCID 86713795HCID 86713795, compound

Reagents, catalysts & solvents 1

HCID 887MethanolSolvent

Procedure

To a solution of 2-(2-methyl-4-nitro-pyrazol-3-yl)tetrahydropyran-4-one (300 mg, 1.33 mmol) in DCM (12 mL) at −70° C. was added boron trifluoride etherate (0.75 mL, 1.73 mmol) dropwise followed by a (trimethylsilyl)diazomethane solution (2 M in hexanes, 0.87 mL, 1.73 mmol). The reaction mixture was stirred at −70° C. for 90 min, quenched with water (10 mL), diluted with DCM (12 mL) and warmed to room temperature. The organic layer was passed through a phase separation cartridge and concentrated under reduced pressure. Purification via silica gel column chromatography (0-100% EtOAc/isohexane) gave 7-(1-methyl-4-nitro-1H-pyrazol-5-yl)oxepan-4-one as a colourless solid (121 mg) and its regioisomer 2-(1-methyl-4-nitro-1H-pyrazol-5-yl)oxepan-4-one (151 mg). To a solution of 7-(1-methyl-4-nitro-1H-pyrazol-5-yl)oxepan-4-one (121 mg, 0.51 mmol) in MeOH (5 mL) at 0° C. was added portionwise NaBH4 (23 mg, 0.61 mmol). Stirring continued for 1 hr and the reaction mixture was quenched with 1 M HCl (5 mL) and EtOAc (10 mL). The aqueous layer was extracted with EtOAc (3×20 mL) and the combined organic layers were washed with brine (30 mL), separated, dried over Na2SO4 and concentrated under reduced pressure to give 7-(2-methyl-4-nitro-pyrazol-3-yl)oxepan-4-ol as a 1:1 mixture of diastereomers as a colourless oil (85 mg, 27% over two steps). The product was used without further purification as a 1/1 mixture of diastereoisomers. 1H NMR (400 MHz, CDCl3) δ 8.02 and 8.01 (s, 1H), 5.61-5.56 and 5.54-5.50 (m, 1H), 4.26-4.14 (m, 1H), 4.07 and 4.04 (s, 3H), 3.90-3.80 and 3.81-3.63 (m, 1H), 2.20-1.80 (m, 8H).

Workup

  1. customthe reaction mixture was quenched with 1 M HCl (5 mL) and EtOAc (10 mL)
  2. extractionThe aqueous layer was extracted with EtOAc (3×20 mL)
  3. washthe combined organic layers were washed with brine (30 mL)
  4. customseparated
  5. dry with materialdried over Na2SO4
  6. concentrationconcentrated under reduced pressure

Sources & evidence

ORD record
ord-895d3814fe4949e4881260c14cacb618
Source dataset
uspto-grants-2016_05
Patent number
US09328106B2

Reaction notes

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