1,2,3,4-Tetrahydroquinoline

Chemical Properties

Clear pale yellow to yellow liquid. It is easily oxidized in air and may acquire a pale amber colour if exposed to air and daylight. Solidifies in the cold.

Uses

1,2,3,4-Tetrahydroquinoline is a reagent used in the synthesis of N-substituted benzoyl-1,2,3,4-tetrahydroquinolyl-1-carboxamides displaying fungicidal activity.

Definition

ChEBI: A member of the class of quinolines that is the 1,2,3,4-tetrahydro derivative of quinoline.

Synthesis Reference(s)

Chemical and Pharmaceutical Bulletin, 34, p. 3905, 1986 DOI: 10.1248/cpb.34.3905
Tetrahedron, 52, p. 1631, 1996 DOI: 10.1016/0040-4020(95)00991-4

Synthesis

1,2,3,4-Tetrahydroquinoline is synthesised using quinoline N-oxide as a raw material by chemical reaction. The specific synthesis steps are as follows:
General procedure: In a 1.5 mL reaction vial, B(C6F5)3 (0.025 mmol, 5.0 mol %) was dissolved in chloroform (0.60 mL), towhich diethylsilane (1.75 mmol, 3.5 equiv) was added. After shaking briefly, quinolines (1a-p, 0.50 mmol, 1.0equiv) was subsequently added to the above catalyst solution under argon atmosphere. The reaction mixturewas stirred at 25-65 oC for 6-24 h for the reaction of 1a-h, and at 25-100 oC for 2-24 h for the reaction of 1i-p,then allowed to cool down to room temperature and concentrated under reduced pressure to give the crudeproduct. This reaction mixture was then treated with 0.25 N HCl ethereal solution (7 mL) and stirred at roomtemperature for 1 h to give the solid residue, which was subsequently washed with ether. The solid residue wasthen dissolved or suspended in MeOH (1.0 mL) and neutralized with Na₂CO₃·H₂O (0.5 g) at 0 oC. After stirringfor 2 h, MeOH was removed under reduced pressure, and the neutralized reaction residue was dissolved inCH₂Cl₂ and washed with brine (5 mL) and water (5 mL). The crude product was then obtained from the organicphase of CH₂Cl₂ solution and finally purified by column chromatography on silica gel to give 2a-h(EtOAc/Hexane = 1/9) and 2i-p (EtOAc/Hexane = 3/7).