Hydrogen Peroxide → 5-(Prop-2-en-1-yl)cyclopent-2-en-1-one

An ice cold (3° C.) solution of 2-phenylselenyl-5-(propene-3-yl)cyclopentanone, (mixture of isomers, (12.0 g, 43 mmol)) in methylene chloride (200 mL) was stirred in a 1 L round bottomed-flask that was equipped for boil-over containment. To this solution was added saturated aqueous ammonium chloride (45 mL), followed by dropwise addition of a 30% aqueous solution of hydrogen peroxide (22 mL). The reaction mixture was then slowly warmed to room temperature with intermittent cooling, as necessary, to prevent excess bubbling and boil-over. After stirring at room temperature for an additional hour the solution was washed with water (100 mL), followed by stirring with 10% aqueous sodium thiosulfate pentahydrate (75 mL) for 10 min, and the aqueous and organic layers were then allowed to separate. The organic solution was washed with saturated aqueous sodium bicarbonate and brine (75 mL each), dried using Na2SO4 and concentrated to a volume of about 30 mL. Purification of the crude reaction was effected by loading the crude mixture onto a silica gel column (˜400 cc) using methylene chloride as the eluting solvent. Concentration of the appropriate fractions afforded 5-(propene-3-yl)cyclopent-2-enone (3.95 g, 75%) as a very pale yellow oil. NMR (CDCl3): δ 7.61 (m, 1 H), 6.12 (m, 1 H), 5.60-5.75 (m, 1 H), 4.90-5.05 (m, 2 H), 2.70-2.80 (m, 1 H), 2.45-2.55 (m, 1 H), 2.30-2.40 (m, 2 H), 2.05-2.15 (m, 1 H).

1. customwas equipped for boil-over containment
2. customas necessary, to prevent excess bubbling
3. stirringAfter stirring at room temperature for an additional hour the solution
4. washwas washed with water (100 mL)
5. stirringby stirring with 10% aqueous sodium thiosulfate pentahydrate (75 mL) for 10 min
6. customto separate
7. washThe organic solution was washed with saturated aqueous sodium bicarbonate and brine (75 mL each)
8. customdried
9. concentrationconcentrated to a volume of about 30 mL
10. customPurification of the crude
11. customreaction

ORD record

ord-06a94348c5734c0587751e7d01fe8458

Source dataset

uspto-grants-2015_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09200011B2