Water → 2,2,6,6-Tetramethyl-4-(piperidin-1-yl)-1,2,3,6-tetrahydropyridine

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Reaction Steps

154.7 g of 2,2,6,6-tetramethyl-4-piperidone, 160 g of piperidine and 10.0 g of p-toluenesulphonic acid monohydrate were dissolved in 200 ml of benzene. The solution was refluxed by heating for 8.5 hours, whilst the water formed in situ was removed with a Dean-Stark separator. The reaction mixture was then poured into a mixture comprising 700 ml of water, 200 ml of concentrated aqueous ammonia and 100 g of ice. The organic layer was separated, washed three times with water and then dried over anhydrous magnesium sulphate. After removing the solvent, the residue was distilled under reduced pressure, giving 46.6 g of 1,2,5,6-tetrahydro-2,2,6,6-tetramethyl-4-piperidinopyridine (bp 80°-82° C./1 mmHg).

Provenance & Evidence