Hydrochloric Acid → 5,6,7,8-Tetrahydro-3-methyl-8-quinolinecarbothioamide

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Reaction Steps

A solution of 3-methyl-5,6,7,8-tetrahydroquinoline (1.43 g, 0.01 mole) in benzene (20 ml) was treated with n-butyl-lithium (15% w/w, 4.5 ml, 0.01 mole) and the solution was allowed to stand at room temperature for 0.5 h. The solution was then treated with a suspension of silicon tetraisothiocyanate (1.3 g, 0.005 mole) in benzene (5 ml) at 0° C. After 10 min., water (50 ml) was added and the mixture was stirred for 0.5 h at room temperature and then acidified with conc. HCl. The aqueous layer was separated, washed with ethyl acetate and the pH was adjusted to 10 with solid Na2CO3. The basic mixture was extracted with ethyl acetate (3 × 50 ml) and the combined organic extracts were dried (MgSO4), filtered and evaporated. The residue was triturated with n-hexane to give 3-methyl-5,6,7,8-tetrahydroquinoline-8-thiocarboxamide (0.2 g, 10%).

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