3376-52-1Relevant academic research and scientific papers
Reactions of nitroxides, part 7: Synthesis of novel nitroxide selenoureas
Zakrzewski, Jerzy,Krawczyk, Maria
, p. 549 - 556 (2008)
The reactions of 4-isoselenocyanato-2,2,6,6-tetramethylpiperidine-l-oxyl with selected amines and lower alcohols give the corresponding novel selenoureas and selenocarbamates, all bearing the nitroxyl moiety. Some of the synthesized selenoureas and seleno
Hydrogen/Halogen Exchange of Phosphines for the Rapid Formation of Cyclopolyphosphines
Barrett, Adam N.,Woof, Callum R.,Goult, Christopher A.,Gasperini, Danila,Mahon, Mary F.,Webster, Ruth L.
supporting information, p. 16826 - 16833 (2021/11/04)
The hydrogen/halogen exchange of phosphines has been exploited to establish a truly useable substrate scope and straightforward methodology for the formation of cyclopolyphosphines. Starting from a single dichlorophosphine, a sacrificial proton "donor phosphine"makes the rapid, mild synthesis of cyclopolyphosphines possible: reactions are complete within 10 min at room temperature. Novel (aryl)cyclopentaphosphines (ArP)5 have been formed in good conversion, with the crystal structures presented. The use of catalytic quantities of iron(III) acetylacetonate provides significant improvements in conversion in the context of diphosphine (Ar2P)2 and alkyl-substituted cyclotetra- or cyclopentaphosphine ((AlkylP)n, where n = 4 or 5) formation. Both iron-free and iron-mediated reactions show high levels of selectivity for one specific ring size. Finally, investigations into the reactivity of Fe(acac)3 suggest that the iron species is acting as a sink for the hydrochloric acid byproduct of the reaction.
Phosphine-catalysed reductive coupling of dihalophosphanes
Hering-Junghans, Christian,Schumann, André,Siewert, Jan-Erik
supporting information, p. 15111 - 15117 (2021/11/12)
Classically tetraaryl diphosphanes have been synthesized through Wurtz-type reductive coupling of halophosphanes R2PX or more recently, through the dehydrocoupling of phosphines R2PH. Catalytic variants of the dehydrocoupling reactio
Exploring the Reactivity of Donor-Stabilized Phosphenium Cations: Lewis Acid-Catalyzed Reduction of Chlorophosphanes by Silanes
Pearce, Kyle G.,Borys, Andryj M.,Clark, Ewan R.,Shepherd, Helena J.
, p. 11530 - 11536 (2018/09/21)
Phosphane-stabilized phosphenium cations react with silanes to effect either reduction to primary or secondary phosphanes, or formation of P-P bonded species depending upon counteranion. This operates for in situ generated phosphenium cations, allowing catalytic reduction of P(III)-Cl bonds in the absence of strong reducing agents. Anion and substituent dependence studies have allowed insight into the competing mechanisms involved.
Non-Metal-Catalyzed Heterodehydrocoupling of Phosphines and Hydrosilanes: Mechanistic Studies of B(C6F5)3-Mediated Formation of P-Si Bonds
Wu, Lipeng,Chitnis, Saurabh S.,Jiao, Haijun,Annibale, Vincent T.,Manners, Ian
supporting information, p. 16780 - 16790 (2017/11/28)
Non-metal-catalyzed heterodehydrocoupling of primary and secondary phosphines (R1R2PH, R2 = H or R1) with hydrosilanes (R3R4R5SiH, R4, R5 = H or R3) to produce synthetically useful silylphosphines (R1R2P-SiR3R4R5) has been achieved using B(C6F5)3 as the catalyst (10 mol %, 100 °C). Kinetic studies demonstrated that the reaction is first-order in hydrosilane and B(C6F5)3 but zero-order in phosphine. Control experiments, DFT calculations, and DOSY NMR studies suggest that a R1R2HP·B(C6F5)3 adduct is initially formed and undergoes partial dissociation to form an "encounter complex". The latter mediates frustrated Lewis pair type Si-H bond activation of the silane substrates. We also found that B(C6F5)3 catalyzes the homodehydrocoupling of primary phosphines to form cyclic phosphine rings and the first example of a non-metal-catalyzed hydrosilylation of P-P bonds to produce silylphosphines (R1R2P-SiR3R4R5). Moreover, the introduction of PhCN to the reactions involving secondary phosphines with hydrosilanes allowed the heterodehydrocoupling reaction to proceed efficiently under much milder conditions (1.0 mol % B(C6F5)3 at 25 °C). Mechanistic studies, as well as DFT calculations, revealed that PhCN plays a key mechanistic role in facilitating the dehydrocoupling reactions rather than simply functioning as H2-acceptor.
Facile Phenylphosphinidene Transfer Reactions from Carbene–Phosphinidene Zinc Complexes
Krachko, Tetiana,Bispinghoff, Mark,Tondreau, Aaron M.,Stein, Daniel,Baker, Matthew,Ehlers, Andreas W.,Slootweg, J. Chris,Grützmacher, Hansj?rg
supporting information, p. 7948 - 7951 (2017/06/27)
Phosphinidenes [R-P] are convenient P1 building blocks for the synthesis of a plethora of organophosphorus compounds. Thus far, transition-metal-complexed phosphinidenes have been used for their singlet ground-state reactivity to promote selective addition and insertion reactions. One disadvantage of this approach is that after transfer of the P1 moiety to the substrate, a challenging demetallation step is required to provide the free phosphine. We report a simple method that enables the Lewis acid promoted transfer of phenylphosphinidene, [PhP], from NHC=PPh adducts (NHC=N-heterocyclic carbene) to various substrates to produce directly uncoordinated phosphorus heterocycles that are difficult to obtain otherwise.
Cationic 5-phosphonio-substituted N-heterocyclic carbenes
Schwedtmann, Kai,Schoemaker, Robin,Hennersdorf, Felix,Bauzá, Antonio,Frontera, Antonio,Weiss, Robert,Weigand, Jan J.
supporting information, p. 11384 - 11396 (2016/07/26)
2-Phosphanyl-substituted imidazolium salts 2-PR2(4,5-Cl-Im)[OTf] (9a,b[OTf]) (4,5-Cl-Im = 4,5-dichloro-1,3-bis(2,6-di-isopropylphenyl)-imidazolium) (a: R = Cy, b: R = Ph) are prepared from the reaction of R2PCl (R = Cy, Ph) with NHC 8 (4,5-dichloro-1,3-bis(2,6-di-isopropylphenyl)-imidazolin-2-ylidene) in the presence of Me3SiOTf. 5-Phospanyl-substituted imidazolium salts 5-PR2(2,4-Cl-Im)[OTf] (10a,b[OTf]) are obtained in quantitative yield when a slight excess of the NHC 8 is used. 5-Phosphonio-substituted imidazolium salts 5-PR2Me(2,4-Cl-Im)[OTf]2 (14a,b[OTf]2) and 5-PR2F(2,4-Cl-Im)[OTf]2 (16a,b[OTf]2) result from methylation reaction or oxidation of 10a,b[OTf] with XeF2 and subsequent fluoride abstraction. According to our quantum chemical studies the Cl1 atom at the 2-position at the imidazolium ring of dication 14b2+ carries a slightly positive charge and is therefore accessible for nucleophilic attack. Accordingly, the reaction of 14a,b[OTf]2 and 16a,b[OTf]2 with R3P (R = Cy, Ph) affords cationic 5-phosphonio-substituted NHCs 5-PR2Me(4-Cl-NHC)[OTf] (17a,b[OTf]) and 5-PR2F(4-Cl-NHC)[OTf] (18a,b[OTf]) via a SN2(Cl)-type reaction. A series of transition metal complexes such as [AuCl(5-PPh2Me(4-Cl-NHC))][OTf] (19[OTf]), [CuBr(5-PPh2Me(4-Cl-NHC))][OTf] (20[OTf]), [AuCl(5-PPh2F(4-Cl-NHC))[OTf] (21[OTf]) and [RhCl(cod)(5-PPh2Me(4-Cl-NHC))][OTf] (23[OTf]) are prepared to prove the coordination abilities of carbenes 17b[OTf] and 18b[OTf]. The isolation of a rare example of a tricationic bis-carbene silver complex [Ag(5-PPh2Me(4-Cl-NHC))2][OTf]3 (22[OTf]3) is achieved by reacting 14b[OTf] with Cy3P in the presence of AgOTf. NHC 17b[OTf] represents a very effective dehydrocoupling reagent for secondary (R2PH, R = Ph, Cy, iBu) and primary (RPH2, R = Ph, Cy) phosphanes to give diphosphanes of type R4P2 (R = Ph, Cy, iBu) and oligophosphanes R4P4, R5P5 (R = Ph, Cy), respectively. Methylation of 17b+ and subsequent deprotonation reaction with LDA affords the cationic NHO (N-heterocyclic olefin) 35+ of which the gold complex 36+ is readily accessible via the reaction with AuCl(tht).
Selectivity effects in zirconium-catalyzed heterodehydrocoupling reactions of phosphines
Ghebreab, Michael B.,Costanza, Sierra,Waterman, Rory
, p. 668 - 670 (2016/04/20)
Zirconium compounds are known to dehydrocouple phosphines catalytically. An exploration of the factors that may promote selective heterodehydrocoupling was performed, revealing that steric factors are important but do not provide substantial selectivity. It was observed that 5-(Me3SiNCH2CH2)2N(CH2CH2NSiMe2CH2)Zr (1) may be sufficiently Lewis acidic to perform Lewis acid or frustrated Lewis pair catalysis.
1,2-Phosphaborines: Hybrid Inorganic/Organic P-B Analogues of Benzene
Barnard, Jonathan H.,Brown, Paul A.,Shuford, Kevin L.,Martin, Caleb D.
supporting information, p. 12083 - 12086 (2015/10/12)
Photolysis of the cyclic phosphine oligomer [PPh]5 in the presence of pentaarylboroles leads to the formation of 1,2-phosphaborines by the formal insertion of a phenylphosphinidene fragment into the endocyclic C-B bond. The solid-state structur
Metal-free Lewis acid mediated dehydrocoupling of phosphines and concurrent hydrogenation
Dobrovetsky, Roman,Takeuchi, Katsuhiko,Stephan, Douglas W.
, p. 2396 - 2398 (2015/02/05)
The stoichiometric reaction of trityl cation with two equivalents of Ph2PH affords the phosphine stabilized phosphenium salt [Ph2(H)PPPh2][B(C6F5)4] via hydride abstraction, while catalytic amounts of B(p-HC6F4)3 effects catalytic phosphine dehydrocoupling with the liberation of H2. This reaction is accelerated by the presence of olefin or imine, effecting concurrent hydrogenation.
