Methanol → Crisaborole intermediate

HRID 1471618Notes

Reaction equation

HRID 1471618 reaction equation
[OH:1][B:2]1[C:6]2[CH:7]=[CH:8][C:9]([O:11][C:12]3[CH:20]=[CH:19][C:15]([C:16](O)=[O:17])=[CH:14][CH:13]=3)=[CH:10][C:5]=2[CH2:4][O:3]1.B(OC)(OC)OC.CO.C([O-])(O)=O.[Na+]>C1COCC1.CCOC(C)=O>[OH:17][CH2:16][C:15]1[CH:19]=[CH:20][C:12]([O:11][C:9]2[CH:8]=[CH:7][C:6]3[B:2]([OH:1])[O:3][CH2:4][C:5]=3[CH:10]=2)=[CH:13][CH:14]=1

Participants

7

Reactant 4

HCID 887MethanolHCID 8470Trimethyl borateHCID 516892Sodium BicarbonateHCID 25010450Benzoic acid, 4-[(1,3-dihydro-1-hydroxy-2,1-benzoxaborol-5-yl)oxy]-

Product 1

HCID 57969145Crisaborole intermediate

Reagents, catalysts & solvents 2

HCID 8028TetrahydrofuranSolvent2×HCID 8857Ethyl AcetateSolvent

Procedure

To a solution of 4-(1-hydroxy-1,3-dihydro-benzo[c][1,2]oxaborol-5-yloxy)-benzoic acid (200 mg, 0.74 mmol, 1.0 eq.), trimethyl borate (0.5 mL, 4.4 mmol, 6.0 eq.) in THF (7.0 mL) was added borane tetrahydrofuran complex solution (1.5 mL, 1.0 M in THF, 1.5 mmol, 2.0 eq.) dropwise under nitrogen atmosphere. The mixture was stirred at room temperature overnight. The mixture was carefully treated with MeOH (2 mL) and poured into EtOAc (10 mL) and sat. NaHCO3 (10 mL). The layers were separated and the aqueous phase was extracted with EtOAc (3×10 mL). Combined organic extracts was washed with brine (10 mL), dried over MgSO4, filtered and the filtrate was concentrated under reduced pressure. The residue was applied to silica chromatography eluting with MeOH/DCM (0:100 to 10:90) to give 5-(4-hydroxymethyl-phenoxy)-3H-benzo[c][1,2]oxaborol-1-ol as a white solid. LCMS (m/z) 279 (M+23); 1H NMR (DMSO-d6) δ: 9.09 (s, 1H), 7.70 (d, J=8.0 Hz, 1H), 7.34-7.38 (m, J=8.7 Hz, 2H), 7.01-7.05 (m, 2H), 6.96 (dd, J=8.0, 2.1 Hz, 1H), 6.91-6.93 (m, 1H), 5.18 (t, J=5.7 Hz, 1H), 4.91 (s, 2H), 4.49 (d, J=5.7 Hz, 2H).

Workup

  1. customThe layers were separated
  2. extractionthe aqueous phase was extracted with EtOAc (3×10 mL)
  3. washCombined organic extracts was washed with brine (10 mL)
  4. dry with materialdried over MgSO4
  5. filtrationfiltered
  6. concentrationthe filtrate was concentrated under reduced pressure
  7. washeluting with MeOH/DCM (0:100 to 10:90)

Sources & evidence

ORD record
ord-2f467eb9598847d297f64724fee42bfc
Source dataset
uspto-grants-2015_04
Patent number
US09012431B2

Reaction notes

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