2-Isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane → 4-[(ethylthio)methyl]-1-methyl-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole

HRID 339950Notes

Reaction equation

HRID 339950 reaction equation
[CH2:1]([S:3][CH2:4][C:5]1[CH:6]=[N:7][N:8]([CH3:10])[CH:9]=1)[CH3:2].C([Li])CCC.C(O[B:20]1[O:24][C:23]([CH3:26])([CH3:25])[C:22]([CH3:28])([CH3:27])[O:21]1)(C)C>O1CCCC1.CCCCCC>[CH2:1]([S:3][CH2:4][C:5]1[CH:6]=[N:7][N:8]([CH3:10])[C:9]=1[B:20]1[O:24][C:23]([CH3:26])([CH3:25])[C:22]([CH3:28])([CH3:27])[O:21]1)[CH3:2]

Participants

6

Reactant 3

HCID 50177412-Isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolaneHCID 119614244-[(ethylthio)methyl]-1-methyl-1H-pyrazoleHCID 178418339Butyllithium

Product 1

HCID 866814474-[(ethylthio)methyl]-1-methyl-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazoleYield 86%

Reagents, catalysts & solvents 2

HCID 8028TetrahydrofuranSolventHCID 8058HexaneSolvent

Procedure

To a solution of 4-[(ethylthio)methyl]-1-methyl-1H-pyrazole (0.81 g, 5.2 mmol) in tetrahydrofuran (3.0 mL) at 0° C. was added 1.6 M n-butyllithium in hexane (6.3 mL, 10. mmol). The solution was stirred at room temperature for 1 h and then cooled down to −78° C. To the solution was added 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (2.06 mL, 10.1 mmol). The reaction was continued at −78° C. for 0.5 h, then warmed up to 0° C. (taking about 0.5 h). The reaction mixture was quenched with brine, adjusted to PH=6-7 with 1 N HCl aqueous solution, extracted with EtOAc (2×). The combined organic phases were washed with brine, dried over Na2SO4, and concentrated under reduced pressure to give one oil residue which was purified by combi-flash chromatography eluted with EtOAc/hexane (20-100%). The purification gave 1.2 g (86% yield) of the desired product as yellowish oil. LC-MS found: 283.1 (M+H)+.

Workup

  1. temperaturecooled down to −78° C
  2. waitThe reaction was continued at −78° C. for 0.5 h
  3. temperaturewarmed up to 0° C. (taking about 0.5 h)
  4. customThe reaction mixture was quenched with brine
  5. extractionextracted with EtOAc (2×)
  6. washThe combined organic phases were washed with brine
  7. dry with materialdried over Na2SO4
  8. concentrationconcentrated under reduced pressure
  9. customto give one oil residue which
  10. customwas purified by combi-flash chromatography
  11. washeluted with EtOAc/hexane (20-100%)
  12. customThe purification

Sources & evidence

ORD record
ord-dad64f9723df463293755f44e4811e8c
Source dataset
uspto-grants-2014_11
Patent number
US08895571B2

Reaction notes

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