Phosphino‐amine (PN) Ligands for Rapid Catalyst Discovery in Ruthenium‐Catalyzed Hydrogen‐Borrowing Alkylation of Anilines: A Proof of Principle

Abstract

Abstract.A general synthetic protocol for the synthesis of simple phosphinoamine (PN) ligands is described with 19 ligands being isolated in good yields. High-throughput ligand screening uncovered the success of two of these ligands for aromatic-amine alkylations via ruthenium-catalyzed hydrogen borrowing reactions. The combination of N,N'-bis(diphenylphosphino)-N,N'-dimethylpropylenediamine with a ruthenium(II) source and potassium hydroxide (15 mol%) is the optimal system for selective monobenzylations of aromatic amines (method A). Over 70% isolated yields have been achieved for the formation of 14 secondary aromatic amines under mild reaction conditions (120 o C and 1.05 equivalents of benzyl alcohol).On the other hand, N,N-bis(diphenylphosphino)-isopropylamine was the ligand utilized for both selective monomethylation and monoethylation reactions of aromatic amines (method B). Here the alcohol is charged as both the reaction medium and substrate and 9 examples are disclosed with all isolated yields exceeding 70%. These methods have been applied to the synthesis of important synthetic building blocks based on aminoferrocene.

Electrocatalytic Hydrogen Evolution Catalyzed by 3,4‐Toluenedithiolate Nickel Complexes of Bis(diphenylphosphine)amine Ligand Containing An Azahydrophilic Group

“…Solvents were of reagent grade and dried and distilled by using standard procedures. (CH 3 ) 2 N(CH 2 ) 2 N(PPh 2 ) 2 NiCl 2 was prepared according to the literature procedure [28–30] . Elemental analyses were investigated on an Elementar Vario EL cube analyzer.…”

Ruthenium(II)‐NNN‐Pincer‐Complex‐Catalyzed Reactions Between Various Alcohols and Amines for Sustainable C−N and C−C Bond Formation

“…Recently, few Fe and Co, based complexes were also reported for the amine alkylation reaction. However, air and moisture sensitive phosphine based ligands were crucial for many of these homogeneous systems ,,,…”

Bis(diphenylphosphino)amines-containing ruthenium cymene complexes as potential anti-Mycobacterium tuberculosis agents

“…One great advantage of the bis(diphenylphosphino) amines ligands compared to the traditional tertiary phosphines is the easy preparation and the availability of several commercial amines with different properties [17]. The ease of synthesis and the possibility to modulate the substituents on N and P positions can provide a wide range of ligands with different structural and electronic properties and makes the PeNeP ligands even more attractive for chemical applications [6,14].…”