Pentane → [1-(tert-Butoxycarbonyl)-5-{[tert-butyl(dimethyl)silyl]oxy}-1H-indol-2-yl]boronic acid

HRID 431173Notes

Reaction equation

HRID 431173 reaction equation
C([Li])(C)(C)C.CCCCC.[C:11]([O:15][C:16]([N:18]1[C:26]2[C:21](=[CH:22][C:23]([O:27][Si:28]([C:31]([CH3:34])([CH3:33])[CH3:32])([CH3:30])[CH3:29])=[CH:24][CH:25]=2)[CH:20]=[CH:19]1)=[O:17])([CH3:14])([CH3:13])[CH3:12].C[O:36][B:37](OC)[O:38]C.S([O-])(O)(=O)=O.[K+]>O1CCCC1.[Cl-].[NH4+].C(OCC)C>[C:11]([O:15][C:16]([N:18]1[C:26]2[C:21](=[CH:22][C:23]([O:27][Si:28]([C:31]([CH3:34])([CH3:33])[CH3:32])([CH3:29])[CH3:30])=[CH:24][CH:25]=2)[CH:20]=[C:19]1[B:37]([OH:38])[OH:36])=[O:17])([CH3:14])([CH3:13])[CH3:12]

Participants

9

Reactant 5

HCID 8003PentaneHCID 8470Trimethyl borateHCID 516920Potassium bisulfateHCID 23398221HCID 23398221, compoundHCID 178418306HCID 178418306, compound

Product 1

HCID 22285134[1-(tert-Butoxycarbonyl)-5-{[tert-butyl(dimethyl)silyl]oxy}-1H-indol-2-yl]boronic acid

Reagents, catalysts & solvents 3

HCID 3283Diethyl EtherSolventHCID 8028TetrahydrofuranSolventHCID 25517Ammonium ChlorideSolvent

Conditions

Temperature
-78 °C

Procedure

A solution of tert-butyllithium in pentane (1.7 M, 20.7 mL, 35.2 mmol, 1.20 equiv) was added to a solution of 5-(tert-butyl-dimethyl-silanyloxy)-indole-1-carboxylic acid tert-butyl ester (1-5, 10.2 g, 29.3 mmol, 1 equiv) in tetrahydrofuran (100 mL) at −78° C. The resulting light-brown solution was stirred at −78° C. for 30 minutes, then trimethylborate (6.67 mL, 58.7 mmol, 2.00 equiv) was added. The resulting mixture was warmed to 0° C., then diluted with saturated aqueous ammonium chloride solution (100 mL) and ethyl ether (200 mL). The aqueous layer was made acidic with aqueous 10% potassium hydrogensulfate solution. The organic layer was separated, then washed with brine, dried over magnesium sulfate, and concentrated. The residual yellow solid was triturated with hexanes to give 1-(tert-butoxycarbonyl)-5-{[tert-butyl(dimethyl)silyl]oxy}-1H-indol-2-ylboronic acid (1-6) as an off-white solid. 1H NMR (400 MHz, CDCl3) δ 7.84 (d, 1H, J=8.9 Hz), 7.37 (s, 1H), 7.01 (d, 1H, J=2.4 Hz), 6.97 (br s, 2H), 6.88 (dd, 1H, J=9.0, 2.4 Hz), 1.73 (s, 9H), 1.00 (s, 9H), 0.20 (s, 6H).

Workup

  1. temperatureThe resulting mixture was warmed to 0° C.
  2. customThe organic layer was separated
  3. washwashed with brine
  4. dry with materialdried over magnesium sulfate
  5. concentrationconcentrated
  6. customThe residual yellow solid was triturated with hexanes

Sources & evidence

ORD record
ord-f02a0b6898a846668e46adc96579a5d2
Source dataset
uspto-grants-2003_12
Patent number
US06656942B2

Reaction notes

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