Die Darstellung sterisch anspruchsvoller Phosphinoester und ihre Verwendung zur Synthese von Rhodium(I)-und Rhodium(III)-Komplexen [1] / The Preparation of Sterically Demanding Phosphinoesters and their Use for the Synthesis of Rhodium(I) and Rhodium (III) Complexes

1994 ◽  
Vol 49 (12) ◽  
pp. 1659-1673 ◽  
Author(s):  
Werner Wolfsberger ◽  
Wolfgang Burkart ◽  
Sonja Bauer ◽  
Andreas Hampp ◽  
Justin Wolf ◽  
...  
Keyword(s):  
Oxidative Addition ◽  
Carbonyl Complex ◽  
Prepared Compound ◽  
Sterically Demanding ◽  
Alkyne Complexes ◽  
Carboxylic Esters ◽  
Ethylene Derivative ◽  
Secondary Phosphines

Two routes for the preparation of sterically demanding phosphinoesters RR′P(CH2)nCO2Me (n=1,2 or 3) and RR′P(CH2)nCO2Et (n=1 or 2) have been developed: (1) reaction of trimethyl-silyl phosphines RR′PSiMe3 (R=R′=/Pr. rBu) with ω-chloroalkylesters, and (2) hydrophos- phination of secondary phosphines HP(R)Ph (R = Me, Et. Pr. iPr, iBu) with unsaturated carboxylic esters. From iPr2PCH2CO2Me (3) and iPr2PCH2CO2Et (4), a variety of rhodium(I) and rhodium(III) complexes, mainly with alkyne and vinylidene ligands, have been prepared. Compound [RhCl(C8H14)2]2 (19) reacts with four equiv. of 3 to give [RhCl(iPr2PCH2CO2Me)2] (20) which on further treatment with CO affords the carbonyl complex trans-[RhCl(CO)(iPr′>PCH2CO2Me)2] (21). The related ethylene derivative trans-[RhCl(C2H4)(iPr2PCH2CO2Me)2] (23) is obtained from [RhCl(C2H4)2]2 (22) and 3. Compound 20 reacts with H2 and HCl by oxidative addition to yield [RhHXCl(iPr2PCH2CO2Me)2] (24, 25) and with RC≡CR′ to give the alkyne complexes trans-[RhCl(RC≡CR′)(iPr2PCH2CO2Me)2] (26-28). The analogous compounds trans- RhCl(HC≡CR)(iPr2PCH2CO2Me)2] (29, 30), equally prepared from 20 and HC≡CR, both rearrange thermally and photochemically to produce the vinylidene isomers trans-[RhCl(=C=CHR)(iPr2PCH2CO2Me)2] (31, 32). In contrast, propyne reacts with 20 to give the allene complex trans-[RhCl(CH2=C=CH2)(iPr2PCH2CO2Me)2] (33). The synthesis of [RhCl(iPr2PCH2CO2Et)2] (34) and the corresponding alkyne and vinylidene adducts 35 and 36, obtained with HC≡CCO2Me as the substrate, is also described.

ChemInform Abstract: Phosphorus-Carbon Bond Formation in Ditungsten Alkyne Complexes Induced by Oxidative Addition of Chlorodiphenylphosphine.

ChemInform ◽  
1989 ◽  
Vol 20 (47) ◽  
Author(s):  
M. J. MAYS ◽  
M. J. MORRIS ◽  
P. F. REINISCH ◽  
M. MCPARTLIN ◽  
H. R. POWELL
Keyword(s):  
Bond Formation ◽  
Oxidative Addition ◽  
Carbon Bond ◽  
Alkyne Complexes

Phosphorus—carbon bond formation in ditungsten alkyne complexes induced by oxidative addition of chlorodiphenylphosphine

Polyhedron ◽  
1989 ◽  
Vol 8 (13-14) ◽  
pp. 1807-1809 ◽  
Author(s):  
Martin J. Mays ◽  
Michael J. Morris ◽  
Paul F. Reinisch ◽  
Mary McPartlin ◽  
Harold R. Powell
Keyword(s):  
Bond Formation ◽  
Oxidative Addition ◽  
Carbon Bond ◽  
Alkyne Complexes

scholarly journals HARC as an open-shell strategy to bypass oxidative addition in Ullmann–Goldberg couplings

2020 ◽  
Vol 117 (35) ◽  
pp. 21058-21064
Author(s):  
Marissa N. Lavagnino ◽  
Tao Liang ◽  
David W. C. MacMillan
Keyword(s):  
Room Temperature ◽  
Elevated Temperatures ◽  
Large Range ◽  
Aryl Halide ◽  
Oxidative Addition ◽  
Open Shell ◽  
Bond Forming ◽  
Aryl Bromides ◽  
Sterically Demanding ◽  
Rapid Diversification

The copper-catalyzed arylation of unsaturated nitrogen heterocycles, known as the Ullmann–Goldberg coupling, is a valuable transformation for medicinal chemists, providing a modular disconnection for the rapid diversification of heteroaromatic cores. The utility of the coupling, however, has established limitations arising from a high-barrier copper oxidative addition step, which often necessitates the use of electron-rich ligands, elevated temperatures, and/or activated aryl electrophiles. Herein, we present an alternative aryl halide activation strategy, in which the critical oxidative addition (OA) mechanism has been replaced by a halogen abstraction–radical capture (HARC) sequence that allows the generation of the same Cu(III)-aryl intermediate albeit via a photoredox pathway. This alternative mechanistic paradigm decouples the bond-breaking and bond-forming steps of the catalytic cycle to enable the use of many previously inert aryl bromides. Overall, this mechanism allows access to both traditional C–N adducts at room temperature as well as a large range of previously inaccessible Ullmann–Goldberg coupling products including sterically demandingortho-substituted heteroarenes.

Some Problems in the Oxidative Addition and Binding of an Ethylene to a Transition Metal Center.

1987 ◽  
Vol 6 (4) ◽  
pp. 902-902
Author(s):  
Jerome Silestre ◽  
Maria Calhorda ◽  
Roald Hoffman ◽  
Page Stoutland ◽  
Robert Bergman
Keyword(s):  
Transition Metal ◽  
Oxidative Addition ◽  
Metal Center

Reversible Oxidative-Addition and Reductive-Elimination of Thiophene from a Titanium Complex and Its Thermally-Induced Hydrodesulfurization Chemistry

2019 ◽  
Author(s):  
Alejandra Gomez-Torres ◽  
J. Rolando Aguilar-Calderón ◽  
Carlos Saucedo ◽  
Aldo Jordan ◽  
Alejandro J. Metta-Magaña ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Ring Opening ◽  
Thiophene Ring ◽  
Oxidative Addition ◽  
Reductive Elimination ◽  
Thermally Induced ◽  
Titanium Complex

<p>The masked Ti(II) synthon (<sup>Ket</sup>guan)(<i>η</i><sup>6</sup>-Im<sup>Dipp</sup>N)Ti (<b>1</b>) oxidatively adds across thiophene to give ring-opened (<sup>Ket</sup>guan)(Im<sup>Dipp</sup>N)Ti[<i>κ</i><sup>2</sup>-<i>S</i>(CH)<sub>3</sub><i>C</i>H] (<b>2</b>). Complex <b>2</b> is photosensitive, and upon exposure to light, reductively eliminates thiophene to regenerate <b>1</b> – a rare example of early-metal mediated oxidative-addition/reductive-elimination chemistry. DFT calculations indicate strong titanium π-backdonation to the thiophene π*-orbitals leads to the observed thiophene ring opening across titanium, while a proposed photoinduced LMCT promotes the reverse thiophene elimination from <b>2</b>. Finally, pressurizing solutions of <b>2 </b>with H<sub>2</sub> (150 psi) at 80 °C leads to the hydrodesulfurization of thiophene to give the Ti(IV) sulfide (<sup>Ket</sup>guan)(Im<sup>Dipp</sup>N)Ti(S) (<b>3</b>) and butane. </p>

Regioselective Gas-Phase n-Butane Transfer Dehydrogenation via Silica-Supported Pincer-Iridium Complexes

2020 ◽  
Author(s):  
Boris Sheludko ◽  
Cristina Castro ◽  
Chaitanya Khalap ◽  
Thomas Emge ◽  
Alan Goldman ◽  
...  
Keyword(s):  
Gas Phase ◽  
Active Site ◽  
Lower Cost ◽  
Open Systems ◽  
Iridium Complexes ◽  
Terminal Olefin ◽  
Molecular Precursors ◽  
Sterically Demanding ◽  
Olefin Production ◽  
Steam Cracking

<b>Abstract:</b> The production of olefins via on-purpose dehydrogenation of alkanes allows for a more efficient, selective and lower cost alternative to processes such as steam cracking. Silica-supported pincer-iridium complexes of the form [(≡SiO-<sup>R4</sup>POCOP)Ir(CO)] (<sup>R4</sup>POCOP = κ<sup>3</sup>-C<sub>6</sub>H<sub>3</sub>-2,6-(OPR<sub>2</sub>)<sub>2</sub>) are effective for acceptorless alkane dehydrogenation, and have been shown stable up to 300 °C. However, while solution-phase analogues of such species have demonstrated high regioselectivity for terminal olefin production under transfer dehydrogenation conditions at or below 240 °C, in open systems at 300 °C, regioselectivity under acceptorless dehydrogenation conditions is consistently low. In this work, complexes <a>[(≡SiO-<i><sup>t</sup></i><sup>Bu4</sup>POCOP)Ir(CO)] </a>(<b>1</b>) and [(≡SiO-<i><sup>i</sup></i><sup>Pr4</sup>PCP)Ir(CO)] (<b>2</b>) were synthesized via immobilization of molecular precursors. These complexes were used for gas-phase butane transfer dehydrogenation using increasingly sterically demanding olefins, resulting in observed selectivities of up to 77%. The results indicate that the active site is conserved upon immobilization.

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