Pinacol → 1-(tetrahydro-2H-pyran-2-yl)-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole

HRID 1628229Notes

Reaction equation

HRID 1628229 reaction equation
[O:1]1[CH2:6][CH2:5][CH2:4][CH2:3][CH:2]1[N:7]1[CH:11]=[CH:10][CH:9]=[N:8]1.C([Li])CCC.OC(C(O)(C)C)(C)C.[B:25]([O:34][CH:35]([CH3:37])[CH3:36])([O:30][CH:31]([CH3:33])[CH3:32])OC(C)C>C1COCC1>[O:1]1[CH2:6][CH2:5][CH2:4][CH2:3][CH:2]1[N:7]1[C:11]([B:25]2[O:30][C:31]([CH3:32])([CH3:33])[C:35]([CH3:36])([CH3:37])[O:34]2)=[CH:10][CH:9]=[N:8]1

Participants

6

Reactant 4

HCID 6425PinacolHCID 21531Triisopropyl borateHCID 218663101-(2-Tetrahydropyranyl)-1H-pyrazoleHCID 178418339Butyllithium

Product 1

HCID 115872081-(tetrahydro-2H-pyran-2-yl)-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazoleYield 38%

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent

Procedure

To a 500 ml flask was added 1-(tetrahydro-2H-pyran-2-yl)-1H-pyrazole 14.1.A and 100 ml of THF. The solution was cooled to −78° C. at which time butyllithium (52 ml, 83 mmole, 1.6M in hexanes) and pinacol (9.8 g, 83 mmole) were added. The reaction was stirred for 5 minutes at −78 C and then triisopropyl borate (19 g, 103 mmole) was added. The reaction was slowly warmed to room temperature over 90 minutes and then stirred at room temperature for an additional 16 hours at which time the reaction was quenched with NH4Cl aq. (pH ˜7-8), extracted with EtOAc, and purified by silica gel chromatography to give 1-(tetrahydro-2H-pyran-2-yl)-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole 14.1.B (7.2 g, 38% yield).

Workup

  1. additionwere added
  2. stirringstirred at room temperature for an additional 16 hours at which time the reaction
  3. customwas quenched with NH4Cl aq. (pH ˜7-8)
  4. extractionextracted with EtOAc
  5. custompurified by silica gel chromatography

Sources & evidence

ORD record
ord-38f2bf33c62a4edf9d4f10e94fe6cd85
Source dataset
uspto-grants-2014_07
Patent number
US08785468B2

Reaction notes

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