Acetic Anhydride → 3,4-dihydro-1H-pyrrolo[2,1-c][1,4]oxazine-8-carboxylic acid ethyl ester
Reaction equation
C([N:3]1[CH2:8][CH2:7][O:6][CH2:5][CH:4]1[C:9](O)=O)=O.C(OC(=O)C)(=O)C.[C:19]([O:23][CH2:24][CH3:25])(=[O:22])[C:20]#[CH:21]>>[CH2:24]([O:23][C:19]([C:20]1[CH:9]=[CH:4][N:3]2[CH2:8][CH2:7][O:6][CH2:5][C:21]=12)=[O:22])[CH3:25]Participants
4
Conditions
- Temperature
- 120 °C
Procedure
To a mixture of 4-formyl-morpholine-3-carboxylic acid (Comp. No. 1) (43 g, 0.295 mol) and acetic anhydride (410 g, 4 mol) was added ethyl propiolate (190 g, 1.94 mol). The resulting mixture was heated slowly to 120° C., which was accompanied by gas evolution. After heating for 2 h at 120° C., the resulting mixture was concentrated under reduced pressure. The crude product was purified by silica gel chromatography (eluting with up to 25% ethyl acetate in heptane) to give 21.4 g (37%) of pure 3,4-dihydro-1H-pyrrolo[2,1-c][1,4]oxazine-8-carboxylic acid ethyl ester. LC/MS (method 4): Rt=1.10 min; m/z=196.1 (M+H+).
Workup
- temperatureAfter heating for 2 h at 120° C.
- concentrationthe resulting mixture was concentrated under reduced pressure
- customThe crude product was purified by silica gel chromatography (
- washeluting with up to 25% ethyl acetate in heptane)
Sources & evidence
- ORD record
- ord-899a5236f9aa4065abc4853075912ebe
- Source dataset
- uspto-grants-2016_03
- Patent number
- US09284333B2
Reaction notes
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