Amino Olefins Research Articles

Rigid Triptycene-Based Di- and Trinuclear Salicylaldiminato Nickel Cooperative Polymerization Catalysts

A multimetallic structure with a rigid linker can poise more than one catalytically active site in close proximity to control their reaction pathways in ethylene (co)polymerization by intermetallic cooperativity. This elegant concept was mainly limited to bimetallic systems. We report the synthesis of a series of mono-, bi-, and trinuclear salicylaldiminato Ni(II) catalysts based on a triptycene backbone. In ethylene (co)polymerization, the bimetallic nickel catalyst not only showed higher activity than the mononickel catalyst but also achieved an enhanced incorporation rate of α-olefin and the polar amino olefin, while the trimetallic nickel catalysts were thermally robust up to 100 °C and achieved a unique long-chain branching level up to an 81% mole ratio of all. Trinuclear nickel catalysts were found to be very less active for ethylene copolymerization with 1-hexene due to the increased steric hindrance. Although the catalytic result is worse than expected, especially for trinickel complexes, this work is still meaningful for the development of multinuclear catalysts that can mediate important catalytic reactions with enhanced efficiency and cooperativity.

Polar Isotactic and Syndiotactic Polypropylenes by Organozirconium‐Catalyzed Masking‐Reagent‐Free Propylene and Amino–Olefin Copolymerization

AbstractPolar functionalized isotactic and syndiotactic polypropylenes (PPs) are synthesized by direct, masking‐reagent‐free propylene and amino–olefin (AO, CH2=CH(CH2)xNnPr2, x=2, 3, 6) copolymerizations using the activated precatalysts rac‐[Me2Si(indenyl)2]ZrMe2 and [Me2C(Cp)(fluorenyl)]ZrMe2, respectively. Polymerization activities at 25 °C are as high as 4208 and 535 kg/(mol h atm) with AO incorporation up to 4.0 mol % and 1.6 mol %, respectively. Remarkably, introducing the amino‐olefin comonomers significantly enhances stereoselection for both isotactic (mmmm: 59.5 %→91.0 %) and syndiotactic (rrrr: 66.3 %→81.3 %) products.

Polar Isotactic and Syndiotactic Polypropylenes by Organozirconium-Catalyzed Masking-Reagent-Free Propylene and Amino-Olefin Copolymerization.

Polar functionalized isotactic and syndiotactic polypropylenes (PPs) are synthesized by direct, masking-reagent-free propylene and amino-olefin (AO, CH2 =CH(CH2 )x Nn Pr2 , x=2, 3, 6) copolymerizations using the activated precatalysts rac-[Me2 Si(indenyl)2 ]ZrMe2 and [Me2 C(Cp)(fluorenyl)]ZrMe2 , respectively. Polymerization activities at 25 °C are as high as 4208 and 535 kg/(mol h atm) with AO incorporation up to 4.0 mol % and 1.6 mol %, respectively. Remarkably, introducing the amino-olefin comonomers significantly enhances stereoselection for both isotactic (mmmm: 59.5 %→91.0 %) and syndiotactic (rrrr: 66.3 %→81.3 %) products.

Rh(I) Complex with a Tridentate Pyridine–Amino–Olefin Actor Ligand–Metal–Ligand Cooperative Activation of CO2 and Phenylisocyanate under C–C and Rh–E (E = O, N) Bond Formation

We synthesized and characterized the novel olefinic multidentate actor ligand dbap-py. The ligand consists of a 2-methyl pyridine unit and an azepine component fused by an N-alkylation. The coordin...

Scandium‐Catalyzed Self‐Assisted Polar Co‐monomer Enchainment in Ethylene Polymerization

Direct coordinative copolymerization of ethylene with functionalized co-monomers is a long-sought-after approach to introducing polyolefin functionality. However, functional-group Lewis basicity typically depresses catalytic activity and co-monomer incorporation. Finding alternatives to intensively studied group 4 d0 and late-transition-metal catalysts is crucial to addressing this long-standing challenge. Shown herein is that mono- and binuclear organoscandium complexes with a borate cocatalyst are active for ethylene + amino olefin [AO; H2 C=CH(CH2 )n NR2 ] copolymerizations in the absence of a Lewis-acidic masking reagent. Both activity (up to 4.2×102 kg mol-1 ⋅h-1> atm-1> ) and AO incorporation (up to 12 % at 0.2 m [AO]) are appreciable. Linker-length-dependent (n) AO incorporation and mechanistic probes support an unusual functional-group-assisted enchainment mechanism. Furthermore, the binuclear catalysts exhibit enhanced AO tolerance and enhanced long chain AO incorporation.

Scandium‐Catalyzed Self‐Assisted Polar Co‐monomer Enchainment in Ethylene Polymerization

AbstractDirect coordinative copolymerization of ethylene with functionalized co‐monomers is a long‐sought‐after approach to introducing polyolefin functionality. However, functional‐group Lewis basicity typically depresses catalytic activity and co‐monomer incorporation. Finding alternatives to intensively studied group 4 d0 and late‐transition‐metal catalysts is crucial to addressing this long‐standing challenge. Shown herein is that mono‐ and binuclear organoscandium complexes with a borate cocatalyst are active for ethylene + amino olefin [AO; H2C=CH(CH2)nNR2] copolymerizations in the absence of a Lewis‐acidic masking reagent. Both activity (up to 4.2×102 kg mol−1⋅h−1> atm−1>) and AO incorporation (up to 12 % at 0.2 m [AO]) are appreciable. Linker‐length‐dependent (n) AO incorporation and mechanistic probes support an unusual functional‐group‐assisted enchainment mechanism. Furthermore, the binuclear catalysts exhibit enhanced AO tolerance and enhanced long chain AO incorporation.

Cationic Two-Coordinate Complexes of Pd(I) and Pt(I) Have Longer Metal-Ligand Bonds Than Their Neutral Counterparts

Summary One-electron oxidation of known ( t Bu 3 P) 2 M (1, M = Pd; 2, M = Pt) with [Ph 3 C][HCB 11 Cl 11 ] leads to two-coordinate, monovalent cations of the formula [( t Bu 3 P) 2 M][HCB 11 Cl 11 ] (3, M = Pd; 4, M = Pt), which also possess linear geometry but with elongated M–P bonds. Spectroscopic and computational studies consistently show that the unpaired electron of the d 9 configuration of 3 and 4 belongs to largely non-bonding orbitals: the s/d z2 hybrid for Pd and the degenerate d x2-y2 /d xy pair for Pt. We show that molecular-orbital-based arguments alone are incapable of predicting or rationalizing the observed M–P bond lengthening on oxidation; correct prediction and rationalization are achieved only by inclusion of electrostatic and Pauli effects. This emphasizes the dangers of interpreting any perturbative changes in bond metrics solely on the basis of energies and occupancies of molecular orbitals; the inclusion of electrostatic and Pauli components is essential to providing a more complete picture.

η2‐Coordination of a Phosphaalkyne to an Amino Olefin Nickel Complex and Regioselective Catalyzed Cyclooligomerization to Dewar 1,3,5‐Triphosphabenzene

AbstractWe report herein an efficient synthesis of a Dewar‐triphosphabenzene derived from [2+2+2] cycloaddition of three phosphaalkyne molecules promoted by an amino olefin Ni0 complex as the catalyst. Amino diolefin NiI complex 1 serves as a precursor complex that reacts with triphenylmethylphosphaethyne under reducing conditions at low temperature to give Ni0 complex 3 with a coordinated phosphaalkyne in a η2‐mode. The structure of 3 was determined by X‐ray diffraction methods and suggests a bonding situation for the phosphaalkyne that is between a side‐on coordinated C≡P molecule and a metallaphosphacyclopropene structure. The reaction of 3 with a 10‐fold excess of phosphaethylene under reducing conditions at room temperature resulted in the formation of 2,4,6‐tris(triphenylmethyl)‐Dewar‐1,3,5‐triphosphabenzene (4) in good yield.

Bimetallic Coordination Insertion Polymerization of Unprotected Polar Monomers: Copolymerization of Amino Olefins and Ethylene by Dinickel Bisphenoxyiminato Catalysts

Dinickel bisphenoxyiminato complexes based on highly substituted p- and m-terphenyl backbones were synthesized, and the corresponding atropisomers were isolated. In the presence of a phosphine scavenger, Ni(COD)2, the phosphine-ligated syn-dinickel complexes copolymerized α-olefins and ethylene in the presence of amines to afford 0.2-1.3% α-olefin incorporation and copolymerized amino olefins and ethylene with a similar range of incorporation (0.1-0.8%). The present rigid catalysts provide a bimetallic strategy for insertion polymerization of polar monomers without masking of the heteroatom group. The effects of the catalyst structure on the reactivity were studied by comparisons of the syn and anti atropisomers and the p- and m-terphenyl systems.

Evidence for the formation of a metal alkyl intermediate in the zinc mediated intramolecular hydroamination

A diketiminato zinc amide complex, LZnNMe2 (1) [L = CH{(CMe)2(2,6-(i)Pr2C6H3N)2}], was prepared and investigated for the catalytic hydroamination of 2,2-dimethylpent-4-en-1-amine. The reaction with the amino olefin resulted in a transamination reaction and the subsequent insertion of the olefin moiety into the metal-amide bond. However, the reaction stopped at this point providing access to the metal alkyl intermediate, LZnR (R = N[upper bond 1 start]H-CH2-CPh2-CH2-C[upper bond 1 end]H-) (2). The isolation of this primary insertion product further strengthens the widely accepted mechanism for the intramolecular hydroamination.

Amino olefin nickel(i) and nickel(0) complexes as dehydrogenation catalysts for amine boranes

A rare paramagnetic organometallic nickel(I) olefin complex can be isolated using the ligand bis(5H-dibenzo[a,d]cyclohepten-5-yl)amine. This complex and related nickel(0) hydride complexes show very high catalytic activity in the dehydrogenation of dimethylamino borane with release of one equivalent of dihydrogen.

Iridium Olefin Complexes Bearing Dialkylamino/amido PNP Pincer Ligands: Synthesis, Reactivity, and Solution Dynamics

The reaction of [IrCl(COE)2]2 (1, COE = cyclooctene) with pincer ligand HN(CH2CH2PiPr2)2 ((PNP)H) and AgPF6 gives iridium(I) amino olefin complex [Ir(COE)(PNP)H]PF6 (3COE-PF6). Without anion exchange, the stability of 3COE-Cl is highly solvent dependent. In benzene or THF a mixture of amido complex [Ir(COE)(PNP)] (4COE), [IrHCl2(PNP)H] (5), and [IrHCl(C8H13)(PNP)H] (6) with a vinylic cyclooctenyl ligand is obtained. A pathway is proposed that includes concurrent trapping of intramolecular C−H versus intermolecular N−H activation products. 3L-PF6 (L = C2H4, C3H6, CO) are prepared by olefin substitution. Deprotonation with KOtBu gives the corresponding amido complexes [IrL(PNP)] (4L; L = COE, C2H4, CO). Reversible COE C−H activation is proposed to account for the fluxional behavior of 3COE-PF6 in solution as compared with the structural rigidity of 4COE, which points toward strong N→Ir π-donation in the amido complexes.

Ring opening of 2-phenylazetidines with allylsilanes

N-Activated 2-phenylazetidines were opened regioselectively at the benzylic carbon with various allylsilanes or propargylsilane in the presence of BF 3·Et 2O, providing amino olefins, precursors of biomolecules such as phenyl-homo-kainoids.

Synthesis of Pharmacologically Relevant Indoles with Amine Side Chains via Tandem Hydroformylation/Fischer Indole Synthesis.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis of Pharmacologically Relevant Indoles with Amine Side Chains via Tandem Hydroformylation/Fischer Indole Synthesis

[reaction: see text] The sequence of hydroformylation and Fischer indole synthesis starting from amino olefins and aryl hydrazines is described. In a convergent manner, the two units bearing pharmacologically relevant substituents are assembled in the final indolization step. This modular and diversity-oriented approach to tryptamines and homotryptamines can be conducted in water and allows synthesis of branched and nonbranched tryptamines as well as tryptamine-based pharmaceuticals such as the 5-HT1D agonist L 775 606.

Synthesis, Structure, and Catalytic Reactions of 1,2-Bis(indenyl)ethane-Derived Lanthanocenes

The synthesis and structure of meso-[ethylenebis(η5-indenyl)]ytterbium(III) bis(trimethylsilyl)amide (6) and the syntheses of rac- and meso-[[ethylenebis(η5-indenyl)]ytterbium(III) chloride][LiCl(Et2O)2] (4, 5) and rac- and meso-[ethylenebis(η5-indenyl)lutetium(III) chloride][LiCl(Et2O)2] (7, 8) are reported. The complexes are synthesized by the metathesis of dilithiated 1,2-bis(indenyl)ethane with either YbCl3 or LuCl3 in THF followed by solvent exchange with diethyl ether to give [[ethylenebis(η5-indenyl)]LnIII chloride][LiCl(Et2O)2] (Ln = Yb, Lu) in yields of 43% and 30%, respectively. In the Yb case, the major diastereomer formed is meso, while in the lutetium reaction, the rac diastereomer predominated. Complex 6 is synthesized by reaction of meso-[[ethylenebis(η5-indenyl)]ytterbium(III) chloride][LiCl(Et2O)2] with NaN(TMS)2; this material was characterized by X-ray diffraction. Complex 6 catalyzes the cyclic hydroamination of primary amino olefins in excellent yields.

Catalytic Intramolecular Hydroamination of Hindered Alkenes Using Organolanthanide Complexes

The intramolecular hydroamination of hindered alkenes has been developed as a versatile route to heterocyclic systems. The current process utilizes the unhindered catalyst system [CpTMS2LnMe]2 (Ln = Sm, Nd) to effect the cyclization of hindered amino olefins, providing products containing quaternary centers. The process tolerates a wide variety of substitution patterns, allowing the construction of monocyclic as well as fused and bridged bicyclic heterocycles. Two experimental procedures were employed in this study: one without solvent, minimizing waste streams, the other in deuterated solvents, allowing NMR monitoring of the reaction. The yield of each reaction was high, with NMR analysis of the reactions in progress showing clean conversion from starting material to a single product in most cases.

Stereoselection effects in the catalytic hydroamination/cyclization of amino olefins at chiral organolanthanide centers

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStereoselection effects in the catalytic hydroamination/cyclization of amino olefins at chiral organolanthanide centersMichel R. Gagne, Laurent Brard, Vincent P. Conticello, Michael A. Giardello, Charlotte L. Stern, and Tobin J. MarksCite this: Organometallics 1992, 11, 6, 2003–2005Publication Date (Print):June 1, 1992Publication History Published online1 May 2002Published inissue 1 June 1992https://doi.org/10.1021/om00042a012RIGHTS & PERMISSIONSArticle Views753Altmetric-Citations156LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (401 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

Organolanthanide-catalyzed hydroamination. A kinetic, mechanistic, and diastereoselectivity study of the cyclization of N-unprotected amino olefins

This contribution reports the efficient, regiospecific Cp{sup {prime}}{sub 2}LnR (Cp{sup {prime}} = {eta}{sup 5}-Me{sub 5}C{sub 5};R = H, CH(TMS){sub 2}, {eta}{sup 3}-C{sub 3}H{sub 5}, N(TMS){sub 2}; Ln-La,Nd,Sm,Y,Lu)-catalyzed hydroamination/cyclization of the amino olefins H{sub 2}NCHR{sup 1}R{sup 2}CH=CH{sub 2} to yield heterocycles. Kinetic isotope effects are observed for some of the cyclizations. The complexes were synthesized to model species in the catalytic cycle. Two independent molecules crystallize per unit cell with average La-NHCH{sub 3} and La{le}NH{sub 2}CH{sub 3} bond distances of 2.31 (1) and 2.70 (1) {Angstrom}, respectively. The amine-amido complexes undergo rapid intramolecular proton transfer between some of the amine and amido ligands. Intermolecular exchange with free amine is rapid on the NMR time scale at -80 {degrees}C. The ordering of precatalyst activities accords with known olefin insertion reactivities. Diastereoselection in H{sub 2}NCH(CH{sub 3})(CH{sub 2}){sub 2}CH=CH{sub 2}(5) cyclization depends on both lanthanide and ancillary ligation. Mechanistic evidence suggests that olefin insertion into the Ln-N bond of the amine-amido complexes is turnover-limiting and is followed by a rapid protonolysis of the resulting Ln-C bond. The proposed catalytic mechanism invokes parallel manifolds, with one manifold populated at high amine concentrations exhibiting high diastereoselectivity in the cyclization of 5, and with the second, favoredmore » at low substrate concentrations, exhibiting lower diastereoselectivity. The catalyst at high amine concentrations is postulated to be a Ln(amido)(amine){sub 2} complex. 93 refs., 15 figs., 8 tabs.« less

Structure of N,N-disubstituted ?,?-unsaturated ?-amino aldehydes

Study of the IR and1H and13C NMR spectra of N,N-disubstituted α,β-unsaturated α-amino aldehydes showed that in the nature of the electron density distribution these compounds occupy an intermediate position between α-unsubstituted amino olefins and α,β-unsubstituted aldehydes, being significantly closer to the latter.