Reaktion #907

Reaktionsgleichung

NaOH

N-methylhydroxylamine

ethyl α-benzoyl-α-propargylacetate

NaOH

HCl

→

2-methyl-5-phenyl-4-propargylisoxazolin-3-one

Ausbeute 34.5%

Lösungsmittel

water

methanol

ether

water

methanol

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.STIRRINGAfter the mixture had been stirred at -30° C. for 2 h
2. 2
   Temperaturthe mixture was heated
3. 3
   Temperaturat reflux for 1 h
4. 4
   Waschenwashed with 50 mL of water and 50 mL of saturated aqueous NaHCO3
5. 5
   Sonstigedried
6. 6
   SonstigeRemoval of the solvent on the rotovap
7. 7
   workup.WAITleft 1.09 g of an oil which
8. 8
   Sonstigewas purified by flash chromatography on a column of 30 g of silica gel
9. 9
   Wascheneluted successively with 100 mL portions of 20, 30, 40, 50, 60, 70 and 80% ether in hexanes

Vorschrift

A stirred solution of 0.28 g (7.0 mmol) of NaOH in 3 mL of water and 7 mL of methanol was cooled to -30° C. and and a solution of 1.42 g (6.2 mmol) of ethyl α-benzoyl-α-propargylacetate in 2 mL of methanol was added dropwise over 2 min. The mixture was stirred at -30° C. for 10 min and a precooled slurry of 0.54 g (13.5 mmol) of NaOH and 1.02 g (12.2 mmol) of N-methylhydroxylamine in 1.5 mL of water was added in one portion. After the mixture had been stirred at -30° C. for 2 h, a 2 mL portion of conc HCl was added and the mixture was heated at reflux for 1 h. The mixture was allowed to cool to room temperature, diluted-with 150 mL of ether, washed with 50 mL of water and 50 mL of saturated aqueous NaHCO3 and dried. Removal of the solvent on the rotovap left 1.09 g of an oil which was purified by flash chromatography on a column of 30 g of silica gel eluted successively with 100 mL portions of 20, 30, 40, 50, 60, 70 and 80% ether in hexanes to afford 0.46 g of 2-methyl-5-phenyl-4-propargylisoxazolin-3-one (Compound 1) as a white solid, m.p. 85°-87° C.

Quelle