Sulfuric Acid → 5,6,7-Trimethylquinoline-8-carboxaldehyde

Participants

Reaction Conditions

Reaction Steps

n-Butyl lithium (2.1 equiv; 1.55M in hexane) was added slowly to a suspension of 8-bromo-5,6,7-trimethylquinoline (4.2 g) in anhydrous THF (40 ml) under nitrogen at -90° C. After 3 hr a solution of N-formylpiperidine (2.1 equiv) in anhydrous THF (10 ml) was added to the mixture was warmed to -40° C. over ca. 2 hr. A dilute sulfuric acid solution (1N; 20 ml) was added and the mixture was warmed to room temperature. The mixture was made basic by the addition of potassium carbonate and was then extracted with ether. The dried (MgSO4) organic fraction was evaporated and the residue was purified by column chromatography over alumina with carbon tetrachloride/dichloromethane (1:1 v/v) elution to give 5,6,7-trimethylquinoline-8-carboxaldehyde as a pale yellow solid, mp 162° C. Pmr specturm (CDCl3 ; δ in ppm): 2.48 (3H,s); 2.68 (3H,s); 2.74 (3H,s); 7.43-8.96 (3H,m); 11.61 (1H,s).

Provenance & Evidence