Pd/C‐catalyzed one‐pot Suzuki‐Miyaura cross‐coupling/hydrogenation of pyridine derivatives

Abstract

Using bromopyridines and methoxyphenyl boronic acid as starting materials, consecutive Suzuki‐Miyaura cross‐coupling and hydrogenation reactions were undertaken using a heterogeneous Pd/C catalyst in one‐pot manner under mild conditions (balloon‐pressure at room temperature for hydrogenation) with excellent yield. To counter Pd leaching as well as catalyst poisoning, addition of an appropriate amount of H2O was crucial to achieving successful AcOH‐promoted hydrogenation, which ensured a selective reduction of the pyridine rings to the corresponding piperidines.

Selective Excitation of Pd‐decorated Titania Enables Consecutive C−C Couplings and Hydrogenations under Ambient Conditions

“…Incorporating multifunctional heterogeneous photocatalysts into consecutive transformations can improve the atom economy and environmental footprint of the process. An example demonstrates the Suzuki reaction and subsequent hydrogenation of a pyridine ring using heterogeneous Pd/C catalyst, where poisoning effects are overcome by adding excess of catalyst (Pd loadings between 10–80 mol %) in the second step [4] . Nevertheless, examples using a heterogeneous catalyst for sequential coupling and hydrogenation remain uncommon.…”

“…An example demonstrates the Suzuki reaction and subsequent hydrogenation of a pyridine ring using heterogeneous Pd/C catalyst, where poisoning effects are overcome by adding excess of catalyst (Pd loadings between 10-80 mol %) in the second step. [4] Nevertheless, examples using a heterogeneous catalyst for sequential coupling and hydrogenation remain uncommon. Common heterogeneous photocatalysts include inorganic semiconductors, such as TiO 2 , which are frequently decorated with transition metals (e. g. Pd, Au, Ni, Cu) and employed in a variety of one-step organic transformations.…”