Di-tert-butyl dicarbonate → 1-t-Butoxycarbonyl-2,3-dihydro-7-methyl-6-nitroindole

HRID 1275649Notes

Reaction equation

HRID 1275649 reaction equation
[CH3:1][C:2]1[C:3]([N+:11]([O-:13])=[O:12])=[CH:4][CH:5]=[C:6]2[C:10]=1[NH:9][CH2:8][CH2:7]2.[CH3:14][C:15]1[CH:16]=[CH:17][C:18]([N+:24]([O-:26])=[O:25])=[C:19]2[C:23]=1[NH:22][CH2:21][CH2:20]2.[C:27]([O:31][C:32](O[C:35]([O:37][C:38]([CH3:41])([CH3:40])[CH3:39])=[O:36])=[O:33])([CH3:30])([CH3:29])[CH3:28]>C(Cl)Cl>[C:27]([O:31][C:32]([N:22]1[C:23]2[C:19](=[C:18]([N+:24]([O-:26])=[O:25])[CH:17]=[CH:16][C:15]=2[CH3:14])[CH2:20][CH2:21]1)=[O:33])([CH3:30])([CH3:29])[CH3:28].[C:38]([O:37][C:35]([N:9]1[C:10]2[C:6](=[CH:5][CH:4]=[C:3]([N+:11]([O-:13])=[O:12])[C:2]=2[CH3:1])[CH2:7][CH2:8]1)=[O:36])([CH3:39])([CH3:40])[CH3:41]

Participants

6

Reactant 3

HCID 90495Di-tert-butyl dicarbonateHCID 158963682,3-Dihydro-7-methyl-6-nitroindoleHCID 158963697-Methyl-4-nitro-indoline

Product 2

HCID 158963701-t-Butoxycarbonyl-2,3-dihydro-7-methyl-6-nitroindoleHCID 158963761h-Indole-1-carboxylic acid,2,3-dihydro-7-methyl-4-nitro-,1,1-dimethylethyl ester

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent2×

Procedure

The isomeric mixture of 2,3-dihydro-7-methyl-6-nitroindole and 2,3-dihydro-7-methyl-4-nitroindole (6.10 g; 0.0337 mol) is dissolved in methylene chloride (50 mL). To this solution is added N,N-dimethylaminopyridine (4.30 g; 0.0337 mol) and di-t-butyidicarbonate (22.5 g; 0.101 mol). Additional methylene chloride (50 mL) is added and the flask is equipped with a reflux condenser. The solution is allowed to stir overnight under an atmosphere of argon. The methylene chloride solution is extracted with four 100-mL portions of aqueous citric acid and is dried over anhydrous potassium carbonate. The solution is filtered, concentrated by rotary evaporation and dried under vacuum to give an oily, brown solid. The crude mixture is purified by silica gel flash column chromatography using 5% ethyl acetate/hexanes as eluent to give 2.44 g of 1-t-butoxycarbonyl-2,3-dihydro-7-methyl-4-nitroindole as a yellow solid and 2.6 g of 1-t-butoxycarbonyl-2,3-dihydro-7-methyl-6-nitroindole as well as some unseparated material.

Workup

  1. customthe flask is equipped with a reflux condenser
  2. extractionThe methylene chloride solution is extracted with four 100-mL portions of aqueous citric acid
  3. dry with materialis dried over anhydrous potassium carbonate
  4. filtrationThe solution is filtered
  5. concentrationconcentrated by rotary evaporation
  6. customdried under vacuum
  7. customto give an oily, brown solid
  8. customThe crude mixture is purified by silica gel flash column chromatography

Sources & evidence

ORD record
ord-d39ff4cd35254c3b884f15d6cf2304e7
Source dataset
uspto-grants-2000_12
Patent number
US06162818

Reaction notes

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