DMPS-Pd/SiO2

DMPS-Pd/SiO₂ is a dimethylpolysilane (DMPS)-modified palladium catalyst supported on silica gel, which be performed reduction of aromatic and aliphatic nitriles to primary amines under liquid-phase continuous-flow conditions.

• A novel dimethylpolysilane-modified Pd catalyst supported on silica gel.
• Application for reduction of nitriles to primary amines using H₂ gas.

Reduction of nitriles under continuous-flow conditions

Examination of second supports

In the reduction of decanenitrile 1, alumina, silica gel, and carbon (Pd/C) were examined as second supports, silica gel gave the corresponding amine hydrochloride 2 in high yield with no by-products (Table 1, entries 2-6). Interestingly, performing the reaction under batch conditions gave a complex mixture (Table 1, entry 7).

Reduction of aromatic nitriles

The reduction of aromatic nitriles with various functional groups catalyzed by DMPS-Pd/SiO₂ under continuous-flow conditions was examined, giving the corresponding amine hydrochlorides in excellent yields (Figure 1). A dinitrile (isophthalonitrile) could be reduced to the corresponding diamine in an almost quantitative yield.

Reduction of aliphatic nitriles

The reduction of various aliphatic nitriles catalyzed by DMPS-Pd/SiO₂ under continuous-flow conditions was examined, and the corresponding amine hydrochlorides were given in high yields by changing the conditions, such as increasing the hydrogen pressure and amount of the catalyst (Figure 2). Furthermore, an ester group is tolerant under the conditions, giving the amino ester in an almost quantitative yield.

Reduction of benzyl cyanides

Phenethylamine is one of the important bioactive compounds in organic synthesis. Reduction of benzyl cyanides under continuous-flow conditions catalyzed by DMPS-Pd/SiO₂ afforded the corresponding phenethylamine hydrochloride in high yield (Figure 3).

References

1. Saito, Y., Ishitani, H., Ueno, M., Kobayashi, S. : ChemistryOpen, 6, 211 (2017).