Boron trifluoride etherate → 4-Tert-butoxy-cyclopent-2-enone

HRID 2393889

Reaction equation

HRID 2393889 reaction equation
[OH:1][CH:2]1[CH2:6][C:5](=[O:7])[CH:4]=[CH:3]1.ClC(Cl)(Cl)C(=N)O[C:12]([CH3:15])([CH3:14])[CH3:13].B(F)(F)F.CCOCC.C(=O)(O)[O-].[Na+]>C(Cl)Cl>[C:12]([O:7][CH:5]1[CH2:6][C:2](=[O:1])[CH:3]=[CH:4]1)([CH3:15])([CH3:14])[CH3:13]

Participants

6

Reactant 4

HCID 8000Boron trifluoride etherateHCID 516892Sodium BicarbonateHCID 2734700Tert-butyl 2,2,2-trichloroethanimidateHCID 41691604-Hydroxycyclopent-2-en-1-one

Product 1

HCID 110625964-Tert-butoxy-cyclopent-2-enoneYield 40%

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent

Procedure

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) δ 7.44 (dd, 1 H, J=18 Hz), 6.2 (d, 1 H, J=5.4 Hz), 4.8 (m, 1 H), 2.68 (dd, 1 H, J=5.8, 18 Hz), 2.25 (d, 1 H, J=18 Hz), 1.27 (s, 9 H); 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).

Workup

  1. stirringstirred for 22 hours
  2. filtrationfiltered
  3. concentrationThe filtrate is concentrated under vacuum
  4. customthe residue is purified by chromatography (silica gel, 39 g, 20% ethyl acetate/hexane, 600 mL)

Sources & evidence

ORD record
ord-2859cb3aee9b4d07a9e065e2bb622678
Source dataset
uspto-grants-1998_09
Patent number
US05808112

Linked notes

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