Synthesis of the Chiral Triphosphine (S,S)-PhP(CH2CHMeCH2PPh2)2and Its Metal Complexes

Jia, Guochen; Lee, Hon Man; Williams, Ian D.

doi:10.1021/om960217v

Cited by 15 publications

(7 citation statements)

References 22 publications

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“…X-ray crystallography (Figure ) indicated a square-planar complex, − with an elongated C(1)C(1)# distance of 1.432(8) Å due to π-backbonding. The RhP distances of 2.2895(13) Å are similar to a previously reported square-planar PNP rhodium(I) complex, (PNP t Bu)RhCl (PNP t Bu = 2,6-bis(di- tert -butylphosphino-methyl)pyridine) (2.2–2.3 Å). , The olefin in the backbone approaches a perpendicular orientation to the plane defined by P(1), Rh(1), and P(1)# (dihedral angle of 73°), similarly to what was observed for compound 6 .…”

Section: Resultssupporting

confidence: 83%

Coordination of a Hemilabile Pincer Ligand with an Olefinic Backbone to Mid-to-Late Transition Metals

Barrett

Iluc

2014

Inorg. Chem.

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The coordination chemistry of a neutral tPCH═CHP pincer (tPCH═CHP = 2,2'-bis(di-iso-propylphosphino)-trans-stilbene) with metals that form stable complexes in the +1 oxidation state was studied and (tPCH═CHP)CoCl, (tPCH═CHP)CoCl(CO), (tPCH═CHP)RhCl, (tPCH═CHP)Cu(OTf), [(tPCH═CHP)Cu][PF6], and [(tPCH═CHP)Ag][PF6] were synthesized and characterized. In order to determine whether the coordination mode is dependent on the oxidation state of the metal, some +2 metal complexes, (tPCH═CHP)CoCl2 and (tPCH═CHP)FeBr2, were also investigated. The coordination of the olefinic backbone is not observed in (tPCH═CHP)FeBr2, (tPCH═CHP)CoCl2, (tPCH═CHP)Cu(OTf), or [(tPCH═CHP)Ag][PF6], but η(2)-coordination is present in [(tPCH═CHP)CoCl][BAr(F)4], [(tPCH═CHP)FeBr][BAr(F)4], (tPCH═CHP)CoCl, (tPCH═CHP)CoCl(CO), (tPCH═CHP)RhCl, and [(tPCH═CHP)Cu][PF6]. Cobalt(II), iron(II), and copper(I) formed complexes with the ligand in both coordination modes. All metal complexes were characterized by multinuclei NMR spectroscopy, X-ray crystallography, and elemental analysis.

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Section: Resultssupporting

confidence: 83%

Coordination of a Hemilabile Pincer Ligand with an Olefinic Backbone to Mid-to-Late Transition Metals

Barrett

Iluc

2014

Inorg. Chem.

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“…Synthesis and Characterization of the Chiral Ruthenium Complex RuCl 2 (etp*). The catalyst precursors used in this study include the chiral complexes RuCl 2 (ttp*) ( 2 ), RuCl 2 (etp*) ( 3 ), RuCl 2 [( R )-( S )-Pigiphos] ( 4 ) 9 and RuCl 2 [( R )-( S )-S-Pigiphos] ( 5 ) . The new complex 3 was obtained by treatment of RuCl 2 (DMSO) 4 with the ligand ( R )-Ph 2 PCH 2 CH(PPh 2 )CH 2 CH 2 PPh 2 (etp*), which was synthesized according to the procedure shown in Scheme .…”

Section: Resultsmentioning

confidence: 99%

“…Solvents were distilled under dinitrogen over sodium−benzophenone (hexane, diethyl ether, THF), or calcium hydride (dichloromethane). The starting materials RuCl 2 (DMSO) 4 , RuCl 2 (ttp) (ttp = PhP(CH 2 CH 2 CH 2 PPh 2 ) 2 ), RuCl 2 (ttp*) (ttp* = ( S,S )-PhP(CH 2 CHMeCH 2 PPh 2 ) 2 ), RuCl 2 [( R )-( S )-Pigiphos] (Pigiphos = bis{( S )-1-[( R )-2-(diphenylphosphino)ferrocenyl]ethyl}cyclohexylphosphine) and RuCl 2 [( R )-( S )-S-Pigiphos] (S-Pigiphos = bis{( S )-1-[( R )-2-(diphenylphosphino)ferrocenyl]ethyl} sulfide) were prepared according to literature methods. All the other reagents were used as purchased from Aldrich or Strem Chemical Co. Microanalyses were performed by either MHW Laboratories (Phoenix, AZ) or the ISSECC-CNR.…”

Section: Methodsmentioning

confidence: 99%

Styrene Cyclopropanation and Ethyl Diazoacetate Dimerization Catalyzed by Ruthenium Complexes Containing Chiral Tridentate Phosphine Ligands

et al. 1999

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Various five-coordinate ruthenium(II) complexes of the general formula RuCl 2 L, where L is a chiral triphosphine ligand, have been tested as catalyst precursors for the cyclopropanation of styrene using ethyl diazoacetate (EDA) as the carbene source. Some of the complexes investigated have been found to catalyze the cyclopropanation reaction, but the conversions to cyclopropanes and the diastereoselectivities were generally poor. With all the catalyst precursors investigated, the dimerization of ethyl diazoacetate to diethyl maleate or diethyl fumarate largely prevailed over cyclopropanation. The best performance was obtained with the complex RuCl 2 (ttp*) (2; ttp* ) (S,S)-PhP(CH 2 CHMeCH 2 PPh 2 ) 2 ) which gave ca. 21% of cyclopropanes, 42% of olefins, and 1% of metathesis products. The highest enantiomeric excess was 35% for the (Z)-2-phenylcyclopropanecarboxylate. In the presence of silver triflate, 2 gave rise to a much more active and selective catalyst system, as the yield in cyclopropanation products increased up to 84%. Neither the regioselectivity nor the diastereoselectivity was appreciably improved, however. The carbene complexes RuCl 2 (ttp*)(dCHCO 2 Et) and RuCl 2 (ttp)(dCHCO 2 Et), where ttp is the achiral ligand PhP(CH 2 CH 2 CH 2 PPh 2 ) 2 , were isolated and characterized by multinuclear NMR spectroscopy. These carbene complexes were found to react with an excess of ethyl diazoacetate to give exclusively diethyl maleate and diethyl fumarate in a 95:5 ratio. The selective formation of cyclopropanation products was conversely observed upon reaction with styrene in the presence of silver triflate. In the absence of a chloride scavenger, cyclopropanes were still formed together with an appreciable amount of the metathesis product PhHCdCHCO 2 Et.

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“…Compared to other multidentate ligands, chiral trisphosphine ligands have been rarely reported in transition metal catalysis. − In 1995, Togni and co-workers developed chiral PPP ligand PPP-L1 (Pigiphos). A chiral phosphanylferrocene moiety was introduced to both side arms, and a pseudo- C 2 symmetry was formed.…”

Section: Overview Of Chiral Tridentate Ligands For Hydrogenationmentioning

confidence: 99%

Chiral Tridentate Ligands in Transition Metal-Catalyzed Asymmetric Hydrogenation

2021

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Asymmetric hydrogenation (AH) of double bonds has been one of the most effective methods for the preparation of chiral molecules and for the synthesis of important chiral building blocks. In the past 60 years, noble metals with bidentate ligands have shown marvelous reactivity and enantioselectivity in asymmetric hydrogenation of a series of prochiral substrates. In recent years, developing chiral tridentate ligands has played an increasingly important role in AH. With modular frameworks and a variety of functionalities on the side arms, chiral tridentate ligand complexes enable both reactivities and stereoselectivities. Although great achievements have been made for noble metal catalysts with chiral tridentate ligands since the 1990s, the design of chiral tridentate ligands for earth abundant metal catalysts has still been in high demand. This review summarizes the development of chiral tridentate ligands for homogeneous asymmetric hydrogenation. The philosophy of ligand design and the reaction mechanisms are highlighted and discussed as well.

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Synthesis of the Chiral Triphosphine (S,S)-PhP(CH₂CHMeCH₂PPh₂)₂and Its Metal Complexes

Cited by 15 publications

References 22 publications

Coordination of a Hemilabile Pincer Ligand with an Olefinic Backbone to Mid-to-Late Transition Metals

Coordination of a Hemilabile Pincer Ligand with an Olefinic Backbone to Mid-to-Late Transition Metals

Styrene Cyclopropanation and Ethyl Diazoacetate Dimerization Catalyzed by Ruthenium Complexes Containing Chiral Tridentate Phosphine Ligands

Chiral Tridentate Ligands in Transition Metal-Catalyzed Asymmetric Hydrogenation

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