Reaction #2644

Reaction equation

sodium hydroxide

lithium aluminum hydride

lithium iodide

4-tert-butoxy-cyclopent-2-enone

→

title compound

Yield 42.0%

cis-4-tert-butyloxy-cyclopent-2-enol

Yield 42.0%

Solvents

toluene

tert-butyl methyl ether

Conditions

Workup

1. 1
   workup.STIRRINGis stirred for 30 minutes
2. 2
   Filtrationtert-butyl methyl ether (10 mL) and filtered
3. 3
   OtherThe phases of the filtrate are separated
4. 4
   Extractionthe aqueous phase is extracted with tert-butyl methyl ether (15 mL)
5. 5
   Dryingdried over magnesium sulfate
6. 6
   Filtrationfiltered
7. 7
   Concentrationconcentrated under vacuum
8. 8
   OtherThe residue is purified by chromatography (silica gel, 30 g, 33% ethyl acetate/hexane)

Procedure

A slurry of lithium aluminum hydride (55 mg, 1.44 mmol), lithium iodide (1.65 g, 5.76 mmol), tert-butyl methyl ether (2 mL) and toluene (3 mL) is cooled to -15° C. The slurry is treated dropwise with 4-tert-butoxy-cyclopent-2-enone(430 mg, 2.79 mmol, dissolved in 1 mL of toluene) over 5 minutes. The reaction mixture is stirred at -20° C. to -12° C. for 2 hours and then allowed to warm to room temperature and is stirred for 30 minutes. The reaction mixture is then treated sequentially with sodium hydroxide (1N, 1 mL), then tert-butyl methyl ether (10 mL) and filtered. The phases of the filtrate are separated and the aqueous phase is extracted with tert-butyl methyl ether (15 mL). The organic extracts and organic phase is combined, dried over magnesium sulfate, filtered and concentrated under vacuum. The residue is purified by chromatography (silica gel, 30 g, 33% ethyl acetate/hexane) to provide the title compound (183 mg, 42%) as a yellow oil, cis/trans/1-2+1-4 addition, 87/9.8/3.2; 1H NMR (CDCl3) 6 5.9 (m, 1H), 5.8 (m, 1H), 4.6 (m, 1H), 4.5 (m, 1H), 2.7 (m, 1H), 2.0 (d,1H, J=9.6 Hz), 1.5 (d appt, 1H, J=4.5, 14 Hz), 1.2 (s, 9H); 13C NMR (CDCl3) δ136.6, 36, 75.5, 74.4, 74, 44.6, 28.7; νmax 3395, 2974, 2938, 907, 2878, 1389, 1364, 1117, 1169, 1022 cm-1 ; MS (CI) m/e (% relative intensity) 157 (M+H+ -H2O), 57, 83 (100).

Source