Synthesis, Structural Characterization, and Catalytic Activity of Indenyl Tris(N‐pyrrolyl)phosphine Complexes of Ruthenium

Abstract

The synthesis, characterization, and catalytic activity of new ruthenium complexes of the tris(N-pyrrolyl)phosphine ligand [P(pyr) 3 ] are described. The new ruthenium complexes [RuCl(ind)(PPh 3 ){P(pyr) 3 }] and [RuCl(ind){P(pyr) 3 } 2 ] (ind = indenyl, η 5 -C 9 H 7 -) were synthesized in 73 and 63 % isolated yields, respectively, by thermal ligand exchange of [RuCl(ind)(PPh 3 ) 2 ] with P(pyr) 3 . The electronic and steric properties of the new complexes were studied through analysis of the X-ray structures and cyclic voltammetry. The new complexes [RuCl(ind)(PPh 3 )-{P(pyr) 3 }] and [RuCl(ind){P(pyr) 3 } 2 ] and the known complex [RuCl(ind){(PPh 3 ) 2 }] differed only slightly in their steric proper-[a]

Branching out: redox strategies towards the synthesis of acyclic α-tertiary ethers

“…Nishibayashi confirmed the intermediacy of a metal-allenylidene or metal-propargylic intermediate when using a thiolatebridged diruthenium complex (as shown in Scheme 105) and developed a wide range of propargylic substitutions, including the synthesis of a range of a-tertiary ethers utilising a broad range of ruthenium catalysts incorporating both mono-and di-nuclear systems and featuring a range of ligand classes [389][390][391] Bauer also developed mononuclear ruthenium catalysts for analogous processes [392][393][394] and others have reported the applicability of a wide variety of ruthenium complexes for the activation of propargylic alcohols. 395,396 From appropriate precursors, analogous metal-free carbenoid strategies have also been successfully developed.…”

Indenylmetal Catalysis in Organic Synthesis

“…[71] Bauer et al investigated complex 97 for catalytic activity toward OH exchange with OR of terminal propargyl alcohols (Scheme 33). [72] Ty pically,g ood isolated yields could be obtained when primary aliphatic alcohols were used as the nucleophiles for propargylation. Using more sterically…”

Ruthenium complexes of the general formula [RuCl2(PHOX)2] as precatalysts in propargylic substitution reactions

“…Ruthenium complexes are known to form allenylidene complexes from propargylic alcohols [16], and these species can potentially function as intermediates for the substitution of the OH group of propargylic alcohols by nucleophiles [1,2,3]. Consequently, rutheniumcatalyzed transformations of propargylic alcohols have been intensively investigated by us [17,18,19,20] and others [1,3,14,15,21], and have resulted in a variety of catalyst systems for the transformation.…”

“…However, a drawback of some catalyst systems is that they require higher reaction temperatures than 60 °C [17,19]. These high reaction temperatures are undesired, not only due to the energy demand but the difficulties in achieving enantiomeric excesses and in addition to increasing the number of potential side reactions which lower the overall yields.…”

“…These high reaction temperatures are undesired, not only due to the energy demand but the difficulties in achieving enantiomeric excesses and in addition to increasing the number of potential side reactions which lower the overall yields. Despite optimization efforts, catalyst systems investigated in our research group did not result in lower reaction temperatures where temperatures as high as 75 to 90 °C were required for the reactions of terminal propargylic alcohols to proceed within reasonable time frames [17,19]. We recently published a number of ruthenium complexes of the general formula [RuCl 2 (PHOX) 2 ], where PHOX refers to bidentate phosphino oxazoline ligands [22].…”