68683-75-0Relevant academic research and scientific papers
Phosphino-amine (PN) Ligands for Rapid Catalyst Discovery in Ruthenium-Catalyzed Hydrogen-Borrowing Alkylation of Anilines: A Proof of Principle
Broomfield, Lewis Marc,Wu, Yichen,Martin, Eddy,Shafir, Alexandr
supporting information, p. 3538 - 3548 (2016/01/25)
A general synthetic protocol for the synthesis of simple phosphino-amine (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 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.
Chiral Recognition in Catalytic Hydrogenation of α-Acylaminoacrylic Acids by Cationic Rhodium(I) Complexes of Chiral Aminophosphines Derived from (R,R)-1,2-Cyclohexanediamine or (R)-1,2-Propanediamine
Kashiwabara, Kazuo,Hanaki, Kazuhiro,Fujita, Junnosuke
, p. 2275 - 2280 (2007/10/02)
Four chiral diphosphines, (R,R)-1,2-biscyclohexane, (R,R)-1,2-bis-cyclohexane, (R)-1,2-bispropane, and (R)-1,2-bispropane have been prepared from the corresponding optically active diamines.The cationic 1,5-cyclooctadiene rhodium(I) complexes with these diphosphines act as effective homogeneous catalysts for the stereoselective hydrogenation of α-acylaminoacrylic acids.The optical yields and the absolute configurations of the products depend on the kind of diphosphine ligands.The (R,R)-1,2-biscyclohexane complex catalyst yields N-benzoyl-(S)-leucine, N-benzoyl-(S)-phenylalanine, and N-acetyl-(S)-phenylalanine in 94, 92, and 89percent e.e., respectively.The other three catalysts are less effective (6-74percent e.e.).The aminophosphine complexes with methyl groups on the nitrogen atoms always give (S)-amino acids, those with no methyl group (R)-amino acids.Such a difference in the chiral recognition has been discussed on the basis of circular dichroism spectra and Dreiding molecular models of the rhodium (I) complexes.
