Sulfuric Acid → 1-(1,1-Dimethylethyl) 2-borono-6-[[(1,1-dimethylethyl)dimethylsilyl]oxy]-1H-indole-1-carboxylate

HRID 1786691Notes

Reaction equation

HRID 1786691 reaction equation
[C:1]([O:5][C:6]([N:8]1[C:16]2[C:11](=[CH:12][CH:13]=[C:14]([O:17][Si:18]([C:21]([CH3:24])([CH3:23])[CH3:22])([CH3:20])[CH3:19])[CH:15]=2)[CH:10]=[CH:9]1)=[O:7])([CH3:4])([CH3:3])[CH3:2].C([Li])(C)(C)C.C[O:31][B:32](OC)[O:33]C.[Cl-].[NH4+].OS([O-])(=O)=O.[K+].OS(O)(=O)=O>O1CCCC1.CCCCC.CCOCC>[C:1]([O:5][C:6]([N:8]1[C:16]2[C:11](=[CH:12][CH:13]=[C:14]([O:17][Si:18]([C:21]([CH3:24])([CH3:23])[CH3:22])([CH3:19])[CH3:20])[CH:15]=2)[CH:10]=[C:9]1[B:32]([OH:33])[OH:31])=[O:7])([CH3:4])([CH3:3])[CH3:2]

Participants

10

Reactant 6

HCID 1118Sulfuric AcidHCID 8470Trimethyl borateHCID 25517Ammonium ChlorideHCID 516920Potassium bisulfateHCID 16654571tert-butyl 6-{[tert-butyl(dimethyl)silyl]oxy}-1H-indole-1-carboxylateHCID 178418306HCID 178418306, compound

Product 1

HCID 230924981-(1,1-Dimethylethyl) 2-borono-6-[[(1,1-dimethylethyl)dimethylsilyl]oxy]-1H-indole-1-carboxylateYield 56%

Reagents, catalysts & solvents 3

HCID 3283Diethyl EtherSolventHCID 8003PentaneSolventHCID 8028TetrahydrofuranSolvent

Conditions

Temperature
78 °C

Procedure

To a solution of 1 g 1-(tert-butoxycarbonyl)-6-(tert-butyldimethylsiloxy)indole in 15 mL anhydrous tetrahydrofuran at −78° C. under nitrogen is added tert-butyllithium (2.30 mL of a 1.5 M solution in pentane) over 3 min, and the reaction is stirred at ˜78° C. After 32 min, 0.66 mL trimethylborate are added in one portion, and the reaction is stirred at 0° C. After 2 h, 9 mL saturated aqueous ammonium chloride are added, the mixture diluted with 25 mL ether, and stirred at ambient temperature. The reaction is acidified with 4 mL of a solution made from 10% aqueous KHSO4 (60 mL) and concentrated H2SO4 (2 mL). After stirring for 15 min, the layers are separated and the organics are washed with water (15 mL) and brine (15 mL) successively, dried (Na2SO4), and the solvent is removed under reduced pressure to yield a partially solidified material. The material is washed with hot hexanes (5 mL) and filtered. The collected solid is washed with hexanes (2×5 mL) to give 635 mg (56%) of 1-(tert-butoxycarbonyl)-6-(tert-butyldimethylsiloxy)indole-2-boronic acid as a white powder.

Workup

  1. stirringthe reaction is stirred at 0° C
  2. waitAfter 2 h
  3. stirringstirred at ambient temperature
  4. stirringAfter stirring for 15 min
  5. customthe layers are separated
  6. washthe organics are washed with water (15 mL) and brine (15 mL) successively
  7. dry with materialdried (Na2SO4)
  8. customthe solvent is removed under reduced pressure
  9. customto yield a partially solidified material
  10. washThe material is washed with hot hexanes (5 mL)
  11. filtrationfiltered
  12. washThe collected solid is washed with hexanes (2×5 mL)

Sources & evidence

ORD record
ord-bcaa333902f44bb3aba5645c7b8da4fa
Source dataset
uspto-grants-2009_03
Patent number
US07507734B2

Reaction notes

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