Sodium Hydroxide → 8-Bromoquinoline-4-carbaldehyde

Participants

Reaction Conditions

Reaction Steps

As shown in step 9-iii of Scheme 9, selenium dioxide (764.7 g, 6.754 mol) was taken up in 3.25 L of dioxane and 500 mL of water. The stirred solution was heated to 77° C. and 8-bromo-4-methylquinoline (compound 2030, 500 g, 2.251 mol) was added in one portion. The reaction mixture was stirred at reflux for 30 minutes and then cooled with a water bath to about 45° C., at which temperature a precipitate was observed. The suspension was filtered through diatomaceous earth which was subsequently washed with the hot THF to dissolve any residual solids. The filtrate was concentrated to a minimum volume under reduced pressure and 2M NaOH (2.81 L, 5.63 mol) was added to achieve a pH of 8 to 9. The reaction mixture was stirred at this pH for 30 minutes. A precipitate resulted which was collected by filtration and air-dried overnight to produce 8-bromoquinoline-4-carbaldehyde (compound 2031) as an yellowish solid: MS=236.16 (M+H); 1H NMR (300 MHz, CDCl3) δ 10.52 (s, 1H), 9.34 (d, J=4.2 Hz, 1H), 9.05 (dd, J=8.5, 1.2 Hz, 1H), 8.18 (dd, J=7.5, 1.3 Hz, 1H), 7.88 (d, J=4.2 Hz, 1H), 7.60 (dd, J=8.5, 7.5 Hz, 1H). This material was used as is in subsequent reactions.

Provenance & Evidence