Reusable Supported Ruthenium Catalysts for the Alkylation of Amines by using Primary Alcohols

Abstract

Efficient and recyclable ruthenium catalysts were synthesized from readily available polystyrene‐ or silica‐supported phosphine ligands. Catalysts bound to the polymer support through an ether linkage showed good to excellent activity towards the N‐alkylation of primary and secondary amines to afford the alkylated products in 62–99 % yield at 120–140 °C. The supported phosphine ligand/ruthenium ratio was found to be crucial for higher catalytic activity and lower ruthenium leaching. The continuous flow N‐alkylation of amines was demonstrated by using the supported catalyst in a column reactor. By adopting the hydrogen‐borrowing strategy, the synthesis of the anti‐Parkinson agent Piribedil was established in 98 % yield at 140 °C.

Catalyst Evolution in Ruthenium-Catalyzed Coupling of Amines and Alcohols

“…We divide the known catalysts into three structural groups. First, some catalysts are formed in situ from a metal precursor (such as Ru 3 (CO) 12 , − [RuCl 2 (η 6 - p -cymene)] 2 , − [RuCl 2 (COD)] n , RuCl 2 (PPh 3 ) 3 , [Cp*RuCl 2 ] 2 , or RuCl 3 · x H 2 O) and a phosphine. Second, some proceed from arene complexes, e.g.…”

Borrowing Hydrogen Amination Reactions: A Complex Analysis of Trends and Correlations of the Various Reaction Parameters

“…A full comparison of such catalysts is provided in tabular form in the SI (Table S6). Catalysts of this type are described in refs ,,− .…”

“…A tabular comparison of the reaction conditions for different reaction types (Figure ) of the target process is provided in SI (Table S10). The literature cited included refs , , , , , , , , , , − , − , , , − , , , − , , , , − , , , , , − , , , , , ,,, , , , − , , , , , , , , , , , , , , − , , − …”

Symmetrical Tertiary Amines: Applications and Synthetic Approaches

“…In 2014 Ramalingam and co‐authors developed a heterogeneous ruthenium catalyst for the borrowing hydrogen reaction. [ 135 ] This catalyst was prepared by reaction of [(cymene)RuCl 2 ] 2 with phosphines, immobilized on the polymeric support. The resulting complex can catalyze borrowing hydrogen amination without addition of bases.…”