Benzyl Bromide → 2-benzyl-7,8-dihydrocyclopenta[e]indazol-6(2H)-one

Participants

Reaction Conditions

Reaction Steps

To a suspension of 7,8-dihydrocyclopenta[e]indazol-6(3H)-one (6.00 g, 34.8 mmol) in 60 mL of dimethylformamide was added benzyl bromide (5.40 mL, 45.5 mmol) and the mixture was heated to 100° C. After 15 hours, the solution was cooled to room temperature and partitioned between chloroform and saturated aqueous NaHCO3. The organic phase was washed with water (3×) and brine and dried over Na2SO4. The solution was concentrated to low volume under vacuum and flash chromatographed on silica gel eluting with EtOAc/dichloroethane (0:100 to 20:80) which removed a minor amount (˜10%) of the faster eluting regioisomer 3-benzyl-7,8-dihydrocyclopenta-[e]indazol-6(3H)-one and gave 2-benzyl-7,8-dihydrocyclopenta[e]indazol-6(2H)-one as a pale yellow solid.

Provenance & Evidence