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

Participants

Reaction Steps

A mixture of 1-(5-bromo-2-hydroxy-phenyl)-ethanone (15.8 g, 73.8 mmol), cyclopentanone (12.35 g, 147 mmol) and pyrrolidine (12 mL, 140 mmol) in MeOH (300 mL) was stirred at room temperature overnight. The mixture was concentrated in vacuo to give the residue, which was added water and HCl (36%) until pH=1. The mixture was extracted with EtOAc and then the organic layer was concentrated to give 6-bromospiro[chroman-2,1′-cyclopentan]-4-one (23 g, 100%). 1H-NMR (CDCl3): 1.64 (m, 4H), 1.72 (m, 2H), 2.03 (m, 2H), 2.78 (s, 2H), 6.78 (m, 1H), 7.48 (m, 1H), 7.91 (m, 1H).

Provenance & Evidence