Cyclopropylamine → 5-bromo-2-cyclopropyl-3-methyl-2H-indazole

Participants

Reaction Conditions

Reaction Steps

To a solution of 1-(5-bromo-2-nitrophenyl)ethanone (4.0 g) in toluene (41 ml) were added cyclopropylamine (2.3 ml) and titanium(IV) tetraisopropoxide (14.4 ml) at room temperature, and the mixture was stirred at 60° C. for 17 hr. The reaction mixture was concentrated, triethyl phosphite (8.4 ml) was added to the residue, and the mixture was stirred at 150° C. for 5 hr. The reaction mixture was cooled, and diluted with ethyl acetate, and 1 M aqueous sodium hydroxide solution was added. The resulting insoluble solid was filtered off, and the filtrate was extracted with ethyl acetate. The organic layer was washed with saturated brine, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The obtained residue was purified by silica gel column chromatography (hexane/ethyl acetate) to give the title compound (2.6 g).

Provenance & Evidence