Trifluoroacetic acid → ethyl (4R)-4-methyl-1-oxo-1,2,3,4-tetrahydropyrazino[1,2-a]indole-7-carboxylate

HRID 1748249Notes

Reaction equation

HRID 1748249 reaction equation
C([O:5][C:6]([NH:8][CH2:9][C@H:10]([N:12]1[C:20]2[C:15](=[CH:16][CH:17]=[C:18]([C:21]([O:23][CH2:24][CH3:25])=[O:22])[CH:19]=2)[CH:14]=[C:13]1C(OCC)=O)[CH3:11])=O)(C)(C)C.C(O)(C(F)(F)F)=O.C([O-])([O-])=O.[K+].[K+]>C(Cl)Cl.C(O)C>[CH3:11][C@H:10]1[N:12]2[C:20]3[CH:19]=[C:18]([C:21]([O:23][CH2:24][CH3:25])=[O:22])[CH:17]=[CH:16][C:15]=3[CH:14]=[C:13]2[C:6](=[O:5])[NH:8][CH2:9]1

Participants

6

Reactant 3

HCID 6422Trifluoroacetic acidHCID 11430Potassium CarbonateHCID 67235704diethyl 1-{(2R)-1-[(tert-butoxycarbonyl)amino]propan-2-yl}-1H-indole-2,6-dicarboxylate

Product 1

HCID 67235470ethyl (4R)-4-methyl-1-oxo-1,2,3,4-tetrahydropyrazino[1,2-a]indole-7-carboxylateYield 74.6%

Reagents, catalysts & solvents 2

HCID 702EthanolSolventHCID 6344DichloromethaneSolvent

Procedure

To a solution of diethyl 1-{(2R)-1-[(tert-butoxycarbonyl)amino]propan-2-yl}-1H-indole-2,6-dicarboxylate (2.7 g, 6.4 mmol) in CH2Cl2 (10 mL) is added TFA (10 mL). The reaction mixture is stirred for 2 h and the solvent is removed under vacuum. To a solution of the residue in ethanol (30 mL) is added K2CO3 (4.5 g, 32.3 mmol) and the reaction mixture is stirred at room temperature for 16 h. The solvent is evaporated and the residue is taken up in water. To the mixture is added a small amount of diethyl ether followed by heptanes (100 mL). The suspension is filtered to afford the title compound (1.3 g, 57% for two steps) as a solid.

Workup

  1. customthe solvent is removed under vacuum
  2. stirringthe reaction mixture is stirred at room temperature for 16 h
  3. customThe solvent is evaporated
  4. additionTo the mixture is added a small amount of diethyl ether
  5. filtrationThe suspension is filtered

Sources & evidence

ORD record
ord-3f79631ac7064fad8aefb992a4a8ebfa
Source dataset
uspto-grants-2015_10
Patent number
US09150577B2

Reaction notes

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