Reacción #2643

Ecuación de reacción

sodium bicarbonate

tert-butyl trichloroacetimidate

boron trifluoride diethyl etherate

4-hydroxy-2-cyclopentenone

→

title compound

Rendimiento 40.0%

4-tert-butoxy-cyclopent-2-enone

Rendimiento 40.0%

Disolventes

methylene chloride

Condiciones de reacción

Tratamiento posterior

1. 1
   Temperaturato warm to room temperature
2. 2
   workup.STIRRINGstirred for 22 hours
3. 3
   Filtraciónfiltered
4. 4
   ConcentraciónThe filtrate is concentrated under vacuum
5. 5
   Otrothe residue is purified by chromatography (silica gel, 39 g, 20% ethyl acetate/hexane, 600 mL)

Procedimiento

A solution of 4-hydroxy-2-cyclopentenone (1.15 g, 11.7 mmol) in methylene chloride is cooled to 3° C. and treated sequentially with tert-butyl trichloroacetimidate (4.2 mL, 23.7 mmol) and boron trifluoride diethyl etherate (0.15 mL). The reaction mixture is stirred at 3-10° C. for 2 hours and then allowed to warm to room temperature and stirred for 22 hours. The reaction mixture is then treated with sodium bicarbonate (250 mg) and filtered. The filtrate is concentrated under vacuum and the residue is purified by chromatography (silica gel, 39 g, 20% ethyl acetate/hexane, 600 mL) to provide the title compound (355 mg, 40%) as a yellow oil; 1H NMR (CDCl3)δ7.44 (dd, 1H, J=18 Hz), 6.2 (d, 1H, J=5.4 Hz), 4.8 (m, 1H), 2.68 (dd, 1H, J=5.8, 18 Hz), 2.25 (d, 1H, J=18 Hz), 1.27 (s, 9H); IR (neat) νmax 2976, 2936, 1721, 1368, 1352, 1188, 1103, 1161 cm-1 ; MS (CI) m/e (% relative intensity) 155 (M+H+, 22), 99 (100).

Fuente