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Tailoring supported palladium sulfide catalysts through H2-assisted sulfidation with H2S

“…6,8,9 However, the use of unsupported palladium suldes as heterogeneous catalysts in the transformation of organic compounds has been scarcely reported because of their lower catalytic activity and stability compared to supported palladium sulde catalysts. 13,14 Supported palladium suldes are generally prepared through the suldation of supported metallic palladium (or oxide) precursors with H 2 S or Na 2 S. [14][15][16][17][18][19][20][21][22][23] However, the suldation usually leads to supported palladium suldes with amorphous structures or mixed crystal phases. 7,[17][18][19][20][21] The preparation of supported palladium suldes with a single crystal structure seems to be a great challenge.…”

A Benzimidazole-Based N-Heterocyclic Carbene Derived from 1,10-Phenanthroline

“…Addition of more NaBH 3 CN failed to advance the reduction to the desired octahydro product ( 3 ). Further reduction of 2 was likely hampered by the generation of the more basic piperidine-like nitrogen atom, and the acidity of the medium was insufficient to protonate the remaining aromatic nitrogen, a requirement in reductions of π-deficient pyridyl rings. − Performing the reaction in glacial acetic acid as solvent would ensure the double protonation of nitrogens in tetrahydro intermediate 2 , allowing the reduction to continue. Although this set of conditions did initially form octahydro 3 , the product surprisingly reacted further, undergoing diethylation with concomitant decomposition to give the undesired N1,N10 -diethyl-2,3,4,7,8,9-hexahydrophenanthroline ( 8 ) as the only isolable product in low 10% yield .…”

A General Strategy for N-(Hetero)arylpiperidine Synthesis Using Zincke Imine Intermediates

“…Next, we obtained a series of piperidine derivatives by performing reduction and nucleophilic addition reactions to pyridinium salts (Scheme ). , Scheme A shows four examples of PtO 2 hydrogenation reactions forming racemic piperidines. We found that the purity of the pyridinium salt can significantly impact the yield of these processes; attempts to use crude cyclized material were only successful in simple cases, such as 3a (not shown).…”