Reaction #710593

Reaction equation

5,7-dichloro-2-methyl-quinolin-8-ol

selenium dioxide

→

17

5,7-Dichloro-8-hydroxyquinoline-2-carboxaldehyde

Solvents

1,4-dioxane

1,4-dioxane

Conditions

Workup

1. 1
   Temperaturecooled
2. 2
   Filtrationthe solids filtered off (celite)
3. 3
   ConcentrationThe filtrate was concentrated
4. 4
   Washthe residue, after washing with diethyl ether (10 mL×3)

Procedure

A solution of 5,7-dichloro-2-methyl-quinolin-8-ol 16 (1.5 g, 6.58 mmol) in 1,4-dioxane (20 mL) was added dropwise over 3 h to a stirred suspension of selenium dioxide (1.3 g, 11.72 mmol) in 1,4-dioxane (60 mL) at 50-55° C. The resulting mixture was then heated at 80° C. overnight, cooled, and the solids filtered off (celite). The filtrate was concentrated and the residue, after washing with diethyl ether (10 mL×3), gave 17 as a yellow solid (quantitative yield). This material was used in the subsequent step without further purification. 1H NMR (CDCl3, 400 MHz): δ 10.26 (s, 1H), 8.69 (d, J=8.8, 1H), 8.37 (br, 1H), 8.17 (d, J=8.8, 1H), 7.76 (s, 1H).

Source