1,2,3,6-TETRAHYDRO-1-METHYL-4-(2,4,6-TRIMETHOXYPHENYL)-PYRIDINE synthesis

Yield:113225-07-3 90%

Reaction Conditions:

with sulfuric acid;acetic acid at 20 - 25;

Steps:

1 Example 1 : 1-Methyl-4-(2,4,6-trimethoxyphenyl)-1 ,2,3,6-tetrahydropyridine

To a solution of acetic acid (120 mL) and 1 ,3,5-trimethoxybenzene (100 g), was added 68 g of N-methyl-4-piperidone over a period of 1 - 2 h at 20 - 25 °C. To the resulting mixture, 90 mL of cone. H₂S0₄ was added over a period of 1 - 2 h at 20 - 25 °C and maintained for 18 - 20 h till 1 ,3,5-trimethoxybenzene was not more than 5 % by HPLC. After completion of reaction, the mixture was quenched in 1 L of chilled water (5 - 10 °C). The reaction mixture was washed with 200 mL of toluene, aqueous layer was separated and adjusted the pH to 1 1 - 12 using 460 mL of 50 % sodium hydroxide solution at 5 - 10 °C to precipitate out the solid. The resulting solid was filtered, washed with water (2 x 200 mL) and dried under vacuum (NLT 650 mm of Hg) at 50 - 60 °C until moisture content was not more than 0.5 %, to afford the title compound.

References:

WO2014/128524,2014,A1 Location in patent:Page/Page column 17