Hydrochloric Acid → 3-Formyl-1-phenylindazole

Participants

Reaction Steps

To a solution (40 mL) of methyl 1-phenyl-1H-indazole-3-carboxylate (2.25 g) synthesized above in tetrahydrofuran was added dropwise 1.5M diisobutylaluminum hydride toluene solution (26.7 mL) at 0° C., and the mixture was stirred for 1 hr. 1N Hydrochloric acid was added to quench the reaction, and the mixture was extracted with ethyl acetate. The extract was washed with 1N hydrochloric acid and saturated brine, dried over magnesium sulfate, and concentrated under reduced pressure to give a colorless oil. To a solution of the obtained oil in tetrahydrofuran (40 mL) was added active manganese dioxide (8.00 g), and the mixture was stirred at 50° C. for 5 hr. Active manganese dioxide (1.00 g) was additionally added, and the mixture was stirred at 50° C. for 1 hr. Manganese dioxide was filtered off, and the filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography (ethyl acetate:hexane=3:17, volume ratio) to give the title object compound (926 mg, 47%) as a pale-yellow oil.

Provenance & Evidence