4,5,6,7-tetrahydro-1H-indole-2-carbaldehyde → 2,5,5-Trimethyl-4,5,6,7-tetrahydroindole

HRID 1751978Notes

Reaction equation

HRID 1751978 reaction equation
N1C2CCCCC=2C=[C:2]1C=O.C[C:13]1[C:21]2[C:20](=O)[C:19]([CH3:24])([CH3:23])[CH2:18][CH2:17][C:16]=2[NH:15][CH:14]=1.[H-].[Al+3].[Li+].[H-].[H-].[H-]>C1COCC1>[CH3:2][C:14]1[NH:15][C:16]2[CH2:17][CH2:18][C:19]([CH3:23])([CH3:24])[CH2:20][C:21]=2[CH:13]=1

Participants

5

Reactant 3

HCID 65020104,5,6,7-tetrahydro-1H-indole-2-carbaldehydeHCID 184707113,5,5-Trimethyl-4-oxo-4,5,6,7-tetrahydroindoleHCID 21226445Aluminium lithium hydride

Product 1

HCID 674211152,5,5-Trimethyl-4,5,6,7-tetrahydroindoleYield 98%

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent

Procedure

Using a procedure closely analogous to the preparation of 4,5,6,7-tetrahydroindole-2-carboxaldehyde, 3,5,5-trimethyl-4-oxo-4,5,6,7-tetrahydroindole 1.65 g (9.31 mmol) was reduced by 36-hour reflux with lithium aluminum hydride 2.0 g in anh. THF (100 mL) to provide 1.50 g (98%) of 2,5,5-trimethyl-4,5,6,7-tetrahydroindole (light tan crystalline solid) that was formylated with a mixture of anhydrous DMF 20 mL and POCl3 1.5 mL to provide the title aldehyde product 1.669 g (93% overall) as a tan solid. 1H-NMR (d6-DMSO, 400 MHz): 11.31 (br s, 1H), 9.43 (s, 1H), 2.51 (m, 2H), 2.14 (s, 3H), 2.13 (s, 2H), 1.49 (t, 6.6 Hz, 2H), 0.94 (s, 6H)

Workup

  1. waitwas reduced by 36-hour

Sources & evidence

ORD record
ord-3d658aae489b487685c12f54b44f0e57
Source dataset
uspto-grants-2015_10
Patent number
US09162981B2

Reaction notes

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