Ethyl Acetate → Methyl 4-acetoxyindole-2-carboxylate
Reaction equation
[CH2:1]([O:8][C:9]1[CH:17]=[CH:16][CH:15]=[C:14]2[C:10]=1[CH:11]=[C:12]([C:18]([O:20][CH3:21])=[O:19])[NH:13]2)[C:2]1C=CC=CC=1.C(OCC)(=[O:24])C>[Pd]>[C:1]([O:8][C:9]1[CH:17]=[CH:16][CH:15]=[C:14]2[C:10]=1[CH:11]=[C:12]([C:18]([O:20][CH3:21])=[O:19])[NH:13]2)(=[O:24])[CH3:2]Participants
Reactant 2
Product 1
Reagents, catalysts & solvents 1
Conditions
- Temperature
- 25 °C
Procedure
A solution of methyl 4-benzyloxyindole-2-carboxylate (48 g) in ethyl acetate (1 litre) at 50-60° C. was hydrogenated over 5%Pd-C catalyst (4.0 g) at 1 atmosphere pressure for 6 hours, until 3.7 litres of hydrogen was absorbed. The catalyst was filtered off and washed with warm ethyl acetate(100 ml). To the combined filtrates was added acetic anhydride (40 ml) and 4-dimethylaminopyridine (1.0 g), and the solution was stirred for 1 hour at 25° C. Ethanol (15 ml) was added and the solution reduced to halt volume by evaporation in vacuo, then hexane (1 litre) was added to cause crystallisation of the product as white needles (37 g, 93%). NMR d (CD3SOCD3) 2.34 (s, 3H), 3.85 (s, 3H), 6.80 (d, 1H), 7.06 (s, 1H), 7.23 (t, 1H), 7.29-7.35 (m, 1H), 12.1 (bs, 1H); M/z (−) 232 (M-H+).
Workup
- customat 50-60° C.
- customfor 6 hours
- customuntil 3.7 litres of hydrogen was absorbed
- filtrationThe catalyst was filtered off
- washwashed with warm ethyl acetate(100 ml)
- additionTo the combined filtrates was added acetic anhydride (40 ml) and 4-dimethylaminopyridine (1.0 g)
- additionEthanol (15 ml) was added
- customby evaporation in vacuo
- additionhexane (1 litre) was added
- customcrystallisation of the product as white needles (37 g, 93%)
Sources & evidence
- ORD record
- ord-66d863c9eea14e9c81cd4092cff6d8a1
- Source dataset
- uspto-grants-2003_05
- Patent number
- US06569888B1
Reaction notes
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