1H-Indole, 6-methyl- → 6-methyl-2,3-dihydro-1H-indole
Reaction equation
[CH3:1][C:2]1[CH:10]=[C:9]2[C:5]([CH:6]=[CH:7][NH:8]2)=[CH:4][CH:3]=1>CCOCC>[CH3:1][C:2]1[CH:10]=[C:9]2[C:5]([CH2:6][CH2:7][NH:8]2)=[CH:4][CH:3]=1Participants
3
Reactant 1
Product 1
Reagents, catalysts & solvents 1
Conditions
- Temperature
- 22 °C
Procedure
6-Methylindole (2.785 g, 21.2 mmol) in dry Et2O (30 mL) was chilled to 0° C. and a solution of ZnBH4 in Et2O (~1.5 eq.; 215 mL of 0.15M) was added. The mixture was stirred 3 days at 22° C. in darkness and then quenched by addition of 1M aqueous HCl (until no further H2(g) evolved on mixing) followed by basification to pH >10 with 2N NaOH. The ether phase was separated and washed with brine, tided over MgSO4(s), filtered, and concentrated in vacuo to afford >90% pure 6-methyl-indoline as a syrup (2.82 g; GC/MS: RT=0.63 min., M+ =133). This material can be purified by chromatography on silica (25% EtOAc/hexanes) or vacuum distillation but was typically used without further purification. The following indolines were prepared in an analogous manner from the appropriately substituted indoles: