Preparation and application of 1-(benzo[D][1,3]dioxol-5-yl)-2-bromopentan-1-one_Kain Industrial Additive

Background and overview^[1]

1-(Benzo[D][1,3]dioxol-5-yl)-2-bromopentan-1-one Chinese alias 1-(1,3-benzodioxol Cycl-5-yl)-2-bromo-1-pentanone, CAS number 146721-06-4, chemical formula C₁₂H₁₃BrO3. Molecular weight 285.13400. 1-(1,3-benzodioxolane-5-yl)-2-bromo-1-pentanone can be used as a pharmaceutical and chemical synthesis intermediate. If 1-(1,3-benzodioxolane-5-yl)-2-bromo-1-pentanone is inhaled, move patient to fresh air; if skin contact occurs, remove contaminated clothing, Rinse the skin thoroughly with soap and water. If you feel discomfort, seek medical attention. If eye contact occurs, separate the eyelids, rinse with running water or saline, and seek medical attention immediately. If ingested, rinse your mouth immediately. Do not induce vomiting and seek immediate medical attention. Seek medical attention.

Preparation and Application ^[1]

The preparation method of 1-(1,3-benzodioxolane-5-yl)-2-bromo-1-pentanone is as follows: to 1-(benzo[d][1,3]di To a solution of oxol-5-yl)pentanone (25g, 0.12mol) in acetic acid (100ml), a solution of bromine (25.2g, 0.158mol) in acetic acid (100ml) was added dropwise. The reaction mixture was then stirred at room temperature for 2 hours. Acetic acid was removed under high vacuum. Water (200 ml) was added to the mixture and the solution was extracted with dichloromethane (2 x 200 ml). The combined organic layers were washed with saturated NaHCO solution (100 ml), water (100 ml) and brine (100 ml). The dichloromethane solution was dried over Na2SO4, filtered and concentrated to dryness under vacuum. The crude product obtained was purified by silica gel chromatography, eluting with 5% ethyl acetate in hexane, to give the title compound 1-(1,3-benzodioxolane-5-yl)-2-bromo-1- Pentanone (30.5g, 89%).

To a solution of 1-(1,3-benzodioxolane-5-yl)-2-bromo-1-pentanone (10.0g, 35.07mmol) in acetonitrile (100ml), potassium carbonate ( 10.0 g, 72.41 mmol) and (R)-(+)-3-pyrrolidinol (6.3 g, 72.4 mmol) and the mixture was stirred at room temperature under nitrogen overnight. The mixture was then filtered and the solution evaporated to dryness. The crude product obtained was purified by silica gel chromatography, eluting with 50% ethyl acetate in hexane, to give the title compound (RS)-1-(benzo[d][1,3]dioxole-5 -yl)-2-((R)-3-hydroxypyrrolidin-1-yl)pentanone, as a brown foamy solid (6.1 g, 60.0%).

Main reference materials

[1] Randox Laboratories Ltd.; Lowry, Philip; Benchikh, Elouard; McConnell, Ivan; Fitzgerald, Peter Patent: EP2626358 A1, 2013;