Cyclopentanone → 6-Bromospiro[2H-1-benzopyran-2,1′-cyclopentan]-4(3H)-one

Participants

Reaction Steps

A solution of 5-bromo-2-hydroxyacetophenone (31.6 g, 0.1477 mol), cyclopentanone (26 mL, 0.2939 mol) and pyrrolidine (24 mL, 0.288 mol) in methanol (600 mL) was stirred at 25° C. overnight. The mixture was then concentrated to a red oil. Water was added and the solution was adjusted to pH 1 with concentrated hydrochloric acid. The product was extracted with diethylether. The organic layer was evaporated under reduced pressure. The residue was then dissolved in a small volume of methanol. The solution was treated with charcoal, filtered and water was added to the filtrate. The residue was extracted with diethylether. The organic layer was dried over magnesium sulfate and diethylether was evaporated under reduced pressure. The product was used directly in the next step (77%).

Provenance & Evidence