Catalytic hydrogenation in the process of 2-((1-benzylpiperidin-4-yl) methyl)-5,6-dimethoxy-2,3-dihydroinden-1-one hydrochloride synthesis I. Catalyst screening and finding the optimal reaction conditions

Catalytic hydrogenation of 2-((1-benzyl-1,2,3,6-tetrahydropyridin-4-yl)methylene)-5,6-dimethoxy-2,3-dihydroinden- 1-one hydrochloride () to 2-((1-benzylpiperidin-4-yl)methyl)-5,6-dimethoxy-2,3-dihydroinden- 1-one hydrochloride (2) was investigated in the batch-slurry reactor. The 5% Pt/C catalyst was chosen to search the optimal reaction conditions because of its higher catalytic activity compared to other catalysts used in the work. To investigate the catalyst activity, selectivity and stability, the effect of agitation speed, catalyst loading, solvent, temperature, hydrogen pressure and catalyst reuse were studied. The initial rate of hydrogenation increases with the increase of catalyst loading, with the temperature and solvent polarity, if alcohols were used as solvents. The hydrogenation rate decreases with higher hydrogen pressure and that was explained by competitive adsorption of both reactants. The results also indicate that 5% Pt/C is a promising catalyst for 1 hydrogenation because at relatively mild reaction conditions selectivity towards main product was high (98%) and catalyst maintains its activity during successive runs.