Trifluoroacetic acid → 1-Oxa-9-azaspiro[5.5]undec-2-en-4-one

HRID 1478427Notes

Reaction equation

HRID 1478427 reaction equation
[O:1]=[C:2]1[CH:19]=[CH:18][O:17][C:4]2([CH2:9][CH2:8][N:7](C(OC(C)(C)C)=O)[CH2:6][CH2:5]2)[CH2:3]1.C(O)(C(F)(F)F)=O>C(Cl)Cl>[CH2:9]1[C:4]2([O:17][CH:18]=[CH:19][C:2](=[O:1])[CH2:3]2)[CH2:5][CH2:6][NH:7][CH2:8]1

Participants

4

Reactant 2

HCID 6422Trifluoroacetic acidHCID 897085271-Oxa-9-azaspiro[5.5]undec-2-ene-9-carboxylic acid, 4-oxo-, 1,1-dimethylethyl ester

Product 1

HCID 897083431-Oxa-9-azaspiro[5.5]undec-2-en-4-oneYield 239.9%

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent

Procedure

To a solution of tert-butyl 8-oxo-11-oxa-3-azaspiro[5.5]undec-9-ene-3-carboxylate (200 mg, 0.748 mmol) in CH2Cl2 (2.4 mL) was added TFA (0.6 mL, 7.8 mmol). The mixture was stirred at room temperature for 15 min. Solvent was removed. The crude material was evaporated again from toluene (2×) and dried under high vacuum overnight to provide 11-oxa-3-azaspiro[5.5]undec-9-en-8-one (300 mg). 1H NMR (400 MHz, CDCl3) δ 7.34 (d, J=6.1 Hz, 1H), 5.57 (d, J=6.1 Hz, 1H), 3.45 (d, J=11.7 Hz, 2H), 3.34 (dd, J=24.1, 12.7 Hz, 2H), 2.67 (s, 2H), 2.38 (d, J=14.6 Hz, 2H), 1.98 (td, J=14.8, 4.8 Hz, 2H). ESI-MS m/z calc. 167.09, found 168.2 (M+1)+; Retention time: 0.17 minutes (3 minute run).

Workup

  1. customSolvent was removed
  2. customThe crude material was evaporated again from toluene (2×)
  3. customdried under high vacuum overnight

Sources & evidence

ORD record
ord-c23f8b9a0961458fa39b640b967e6802
Source dataset
uspto-grants-2016_08
Patent number
US09403839B2

Reaction notes

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