Synthesis, Palladium(II) Complexes, and Catalytic Use of a Phosphanylferrocene Ligand Bearing a Guanidinium Pendant

Abstract

A polar phosphanylferrocene donor equipped with a hydrophilic guanidinium pendant, Ph 2 PfcCH 2 NHC(NH)NH 2 ·HCl (1·HCl; fc = ferrocene-1,1′-diyl), has been prepared from the corresponding amine hydrochloride, Ph 2 PfcCH 2 NH 2 ·HCl (2·HCl), and studied as a ligand for Pd II

Synthesis and Catalytic Evaluation of Phosphanylferrocene Ligands with Cationic Guanidinium Pendants and Varied Phosphane Substituents

“…The series of cationic phosphanylferrocene guanidine ligands 3 was expanded to include a pair of ligands with electronically and sterically similar electron‐donating alkyl groups (R = i Pr and Cy) and another pair of compounds with flat, conjugated, electron‐withdrawing aryl groups at the phosphorus atom. Specifically, new guanidinium phosphanes 3a , 3b and 3d were synthesized using a modified approach developed to prepare ligand 3c . In the first step, the starting phosphanylnitriles 1 were reduced by Li[AlH 4 ] in THF to give the corresponding phosphanylamines 2 in practically quantitative yields (Scheme ).…”

“…Other chemicals were purchased from Sigma‐Aldrich or Alfa‐Aesar (reagent grade) and used without additional purification. Compounds 1a , 1b , and 1d , and 3c were prepared as described previously. Anhydrous THF and methanol, used during syntheses, were obtained from a Pure Solv MD5 solvent purification system (Innovative Technology, USA).…”

“…Recently, we have reported the facile synthesis of N ‐{[1′‐(diphenylphosphanyl)ferrocene‐1‐yl]methyl}guanidinium chloride (compound 3c in Scheme ) by guanylation of [1′‐(diphenylphosphanyl)ferrocene‐1‐yl]methylamine and preliminary results from catalytic tests of this compound as an auxiliary ligand for Pd‐catalyzed cross‐coupling reactions. To further develop the chemistry of phosphanylferrocene‐guanidine ligands, we aimed to extend the series of such compounds by synthesizing analogues bearing different phosphane substituents, compounds 3 (Scheme ).…”

Synthesis of Hydrophilic Phosphorus Ligands and Their Application in Aqueous‐Phase Metal‐Catalyzed Reactions

“…Guanidinium Groups . Recently, the guanidine moiety as hydrophilic entity was revisited by the group of Štěpnička for the preparation of phosphinylferrocene ligands [58–60] . Taking advantage of a carboxyl group, which can be transformed into its acylbenzotriazole derivative, an acylguanidinium moiety could be efficiently installed (Scheme 23).…”

Synthesis of Two Isomeric Ferrocene Phosphanylcarboxylic Acids and their PdII Complexes with and without Auxiliary ortho‐Metalated C,E‐Ligands (E = N and S)

“…This prompted us to focus on “semi‐homologous” congeners of dppf and the related asymmetric donor derivatives. So far, we have reported the preparation and coordination behavior of diphosphane B (Scheme ) and compounds bearing CH 2 FG fragments (where FG denotes a functional group) in the place of the CH 2 PPh 2 moiety, namely, the phosphanylferrocene pyridine C , amine D , ether E , sulfones F , ureas G , and guanidine H . Notable examples from other laboratories include the imidazolium salts I used to prepare structurally interesting P‐chelated N‐heterocyclic carbene (NHC) complexes and a phosphane donor bearing an axially chiral azepine moiety, compound J …”