2,6-Di-tert-butyl-4-methylphenol → 8-bromo-5H-chromeno[3,4-c]pyridine

Participants

Reaction Conditions

Reaction Steps

A solution of (E)-2-((E)-3-(4-bromo-2-(prop-2-ynyloxy)phenyl)allylidene)-1,1-dimethylhydrazine (116 mg, 374 mmol) and 2,6-di-tert-butyl-4-methylphenol (82 mg, 374 mmol) in mesitylene (4.5 mL) was degassed at 50° C. by bubbling argon for ˜15 min while sonicating in a thick glass vial. The vial was capped under argon and heated to 140° C. in an oil bath with stirring for 138 h (5.75 days). The reaction mixture was cooled to ambient temperature and the solvent was concentrated under reduced pressure. The dark residue was purified by silica gel chromatography with EtOAc:dichloromethane (1:19) as the eluant. Fractions containing the required product were combined and concentrated under reduced pressure to give 8-bromo-5H-chromeno[3,4-c]pyridine (27 mg, 0.088 mmol, 25% yield based on 89% purity) as a pale yellow powder. 1H NMR (500 MHz, CDCl3) δ 8.63 (d, J=5.2 Hz, 1H), 8.45 (s, 1H), 7.62 (d, J=8.2 Hz, 1H), 7.52 (d, J=5.2 Hz, 1H), 7.27-7.22 (m, 2H), 5.20 (s, 2H); LCMS (Method A) (ESI) m/e 262.0, 264.0 Br pattern [(M+H)+, calcd for C14H15BrN2O 262.0].

Provenance & Evidence