Water → Indoline-4-ol

HRID 239202Notes

Reaction equation

HRID 239202 reaction equation
[OH:1][C:2]1[CH:10]=[CH:9][CH:8]=[C:7]2[C:3]=1[CH:4]=[CH:5][NH:6]2.[BH3-]C#N.[Na+].O>C(O)(=O)C>[OH:1][C:2]1[CH:10]=[CH:9][CH:8]=[C:7]2[C:3]=1[CH2:4][CH2:5][NH:6]2

Participants

5

Reactant 3

HCID 962WaterHCID 754211H-indol-4-olHCID 5003444Sodium cyanoborohydride

Product 1

HCID 3021054Indoline-4-ol

Reagents, catalysts & solvents 1

HCID 176Acetic AcidSolvent

Procedure

A solution of 4-hydroxyindole (6.66 g, 50 mmol) in acetic acid (250 mL) was treated with NaBH3CN (9.42 g, 150 mmol) over 0.5 h, keeping the temperature at <15 C. The mixture was then stirred at room temperature for 1 h and water (5 mL) was added and the solvent evaporated. The residue was dissolved in EtOAc (150 mL) and washed with saturated aq. NaHCO3 and brine, dried and evaporated to give 4-hydroxyindoline as pale crystals (6.76 g. 100%); 1H NMR (δ, CDCl3 DMSO-d6): 6.82 (1H, t, J=8 Hz), 6.20 (1H, d, J=8 Hz), 6.16 (1H, d, J=8 Hz), 3.52 (2H, t, J=8 Hz) and 2.90 (2H, d, J=8 Hz). The crude indoline was dissolved in a mixture of acetic acid (50 mL) and acetic anhydride (50 mL) and heated under reflux for 1 h. The solution was diluted with water (10 mL) and the solvents evaporated. The residue was dissolved in EtOAc (150 mL) and washed with saturated aq. NaHCO3 and brine, dried and evaporated to give 4-acetoxy-1-acetylindoline as pale crystals (9.01 g, 82%), NMR (δ, 90 MHz): 8.07 (1H, d, J=8 Hz), 7.19 (1H, t, J=8 Hz), 6.72 (1H, d, J=8 Hz), 4.05 (2H, t, J=8 Hz), 3.03 (2H, t, J=8 Hz) 2.28 (3H, s) and 2.19 (3H, s).

Workup

  1. customthe solvent evaporated
  2. dissolutionThe residue was dissolved in EtOAc (150 mL)
  3. washwashed with saturated aq. NaHCO3 and brine
  4. customdried
  5. customevaporated

Sources & evidence

ORD record
ord-5d3a642152c646efb1c3ec005e0aed9a
Source dataset
uspto-grants-2014_02
Patent number
US08642785B2

Reaction notes

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