Acetic Acid → 7,7-Difluoro-3,4,6,7,8,9-hexahydropyrazino[1,2-a]indol-1(2H)-one

HRID 519331Notes

Reaction equation

HRID 519331 reaction equation
[NH2:1][CH2:2][CH2:3][N:4]1[C:12]2[CH2:11][C:10]([F:14])([F:13])[CH2:9][CH2:8][C:7]=2[CH:6]=[C:5]1[C:15]([O:17]CC)=O.C(O)(=O)C>C1(C)C=CC=CC=1>[F:13][C:10]1([F:14])[CH2:11][C:12]2[N:4]3[CH2:3][CH2:2][NH:1][C:15](=[O:17])[C:5]3=[CH:6][C:7]=2[CH2:8][CH2:9]1

Participants

4

Reactant 2

HCID 176Acetic AcidHCID 86683733Ethyl 1-(2-Aminoethyl)-6,6-difluoro-4,5,6,7-tetrahydro-1H-indole-2-carboxylate

Product 1

HCID 866837357,7-Difluoro-3,4,6,7,8,9-hexahydropyrazino[1,2-a]indol-1(2H)-oneYield 53.3%

Reagents, catalysts & solvents 1

HCID 1140TolueneSolvent

Procedure

Into a 250-mL round-bottom flask was placed a solution of 113n (10 g, 36.73 mmol, 1.00 equiv) in toluene (100 mL) and acetic acid (1.1 g, 18.32 mmol, 0.50 equiv). See FIG. 14. The resulting solution was heated to reflux for 2 h, cooled and concentrated under vacuum. The residue was triturated in 100 mL of dry ether. The crude product was purified by recrystallization from ethanol to afford 4.43 g (53%) of 113o as a white solid. MS-ESI: [M+H]+ 227. 1H NMR (300 MHz, DMSO) δ 2.10-2.24 (2H, m), 2.59-2.64 (2H, m), 3.17-3.27 (2H, m), 3.43-3.48 (2H, m), 3.88-3.92 (2H, m), 6.44 (1H, s), 7.56 (1H, s).

Workup

  1. customInto a 250-mL round-bottom flask was placed
  2. temperatureThe resulting solution was heated
  3. temperatureto reflux for 2 h
  4. temperaturecooled
  5. concentrationconcentrated under vacuum
  6. customThe residue was triturated in 100 mL of dry ether
  7. customThe crude product was purified by recrystallization from ethanol

Sources & evidence

ORD record
ord-16c4a2ad739d46c9ae16cd859821d52c
Source dataset
uspto-grants-2015_08
Patent number
US09115152B2

Reaction notes

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