Fluoroalkenyl, fluoroalkynyl and fluoroalkyl phosphines

A review of the methods available for the preparation of monodentate P(III) compounds containing fluoroalkenyl, fluoroalkynyl and fluoroalkyl groups is given. The synthesis, properties and coordination chemistry of some fluoroalkenyl- and fluoroalkynyl-containing phosphines derived from HFC-134a (CF₃CH₂F) and HFC-245fa (CF₃CH₂CH₂F) is summarised. The development of the reaction between trimethylsilyl-containing phosphines and R_fI which provides a general method by which bulky fluoroalkyl groups, such as i-C₃F₇, t-C₄F₉, c-C₆F₁₁, can be readily introduced into phosphorus(III) centres is reported. Together these methods provide a way of generating P(III) systems of the type R_3−nP(R_f)_n capable of possessing a wide range of steric and electronic properties.     

PN Bond Cleavage during the Insertion of Carbon Fragments into PIIIN Bonds in Bis(diphenylphosphino) Amines

The reaction of tertiary amine functionalized phosphines with aromatic and aliphatic aldehydes gives insertion of carbon fragments into the P^III? N bonds or P^III? N bond cleavage. The reaction of bis(diphenylphosphino) amines, 1a – 1c , with two equiv. of aldehydes in toluene afforded the P^III? N bond inserted products, 2a – 4a, 4b – 6b , and 3c – 5c , in moderate‐to‐good yield. The products were characterized by IR, ¹H‐ and ³¹P‐NMR spectroscopy and elemental analysis.     

Chiral Steroidal Phosphines: Synthesis and Platinum Complexes

Summary.  The synthesis of novel 3- and 17-diphenylphosphino-androstane derivatives via homogeneous catalytic P-C coupling is described. The products were characterized by ¹H and ³¹P NMR measurements. According to the NMR investigation of the PtCl₂P₂-type complexes, the steroidal phosphines are trans-coordinated with respect to the Pt-centre exclusively. Received June 14, 2000. Accepted (revised) July 24, 2000     

Synthesis and Characterization of Mixed-Substituent P- n -Propyl-N-trimethylsilylphosphoranimines

One approach to the synthesis of polyphosphazenes is the condensation polymerization of phosphoranimines. In this work, several novel P-n-propyl-N-trimethylsilylphosphoranimines have been synthesized and characterized. Modifications to the literature synthetic routes were required to obtain the precursor phosphines. The N-trimethylsilylphosphoranimines were obtained though oxidation of the phosphine with bromine and then subsequent nucleophilic displacement using lithium phenoxide. These phosphoranimines were stable for long periods of time under dry inert conditions. NMR analyses revealed complex splitting patterns beyond typical coupling due to the stereocenter at phosphorus. We report several approaches to the n-propyl containing phosphines and phosphoranimines.     

1,3,5‐Triaza‐7‐phosphaadamantane (PTA) Derived Caged Phosphines for Palladium‐Catalyzed Selective Functionalization of Nucleosides and Heteroarenes

Phosphines have, in combination with transition metals, played a pivotal role in the rapid development of efficient catalytic processes. Caged phosphines constitute a class of three‐dimensional scaffolds providing unique control over steric and electronic properties. The versatility of the caged phosphine ligands has been demonstrated elegantly by the groups of Verkade, Gonzalvi as well as Stradiotto. Our research group has also been working extensively for the past several years in the development of 1,3,5‐triaza‐7‐phosphaadamantane‐based caged ligands and in this personal note we have summarized these applications pertaining to the modification of biologically useful nucleosides and heteroarenes.     

Accessibility and Solid State NMR Studies on Sol‐Gel Processed Diphosphine Ligands

Novel xerogels X1 a–d were obtained by sol‐gel processing of the monomeric T‐functionalized diphosphine ligand (MeO)₃Si(CH₂)₆CH[CH₂PPh₂]₂ [1(T⁰)] with various amounts of the co‐condensing agents MeSi(OMe)₂(CH₂)₆(OMe)₂SiMe (D⁰–C₆–D⁰) and MeSi(OMe)₂(CH₂)₃(C₆H₄)(CH₂)₃(OMe)₂SiMe [Ph(1,4‐C₃D⁰)₂] . ²⁹Si CP/MAS NMR spectroscopic investigations were applied to probe the matrices and their degree of condensation. The integrity of the hydrocarbon backbone and diphosphine moiety was examined by means of solid state NMR spectroscopy (¹³C, ³¹P). To study the dynamics of the matrices and the phosphorus centers detailed measurements of relaxation time (T_1ρH) and cross polarization constants (T_SiH, T_PH) were carried out. The accessibility of the polysiloxane‐supported diphosphines was scrutinized by some typical phosphine reactions. It was found that reagents such as H₂O₂, MeI as well as bulky molecules like (NBD)Mo(CO)₄ or (COD)PdCl₂ are able to reach all phosphorus centers independent on the kind of the backbone of the matrix. SEM micrographs show the morphology of the hybrid materials and energy dispersive X‐ray spectroscopy (EDX) suggest that the distribution of the elements agree with the applied composition.     

Synthesis and structural characterization of rac-2-[(diphenylphosphino)methyl]ferrocenecarboxylic acid, its selected derivatives and some rhodium complexes

rac-2-[(Diphenylphosphino)methyl]ferrocenecarboxylic acid (1) was prepared in a good yield from rac-2-(N,N-dimethylaminomethyl)bromoferrocene (2) via rac-2-(hydroxymethyl)bromoferrocene (4) and rac-2-[(diphenylphosphino)methyl]bromoferrocene (5), and further converted to the respective phosphine oxide (6), phosphine sulfide (7) and methyl ester (8). The phosphines 1 and 8 were studied as ligands in rhodium complexes. The reaction of di-μ-chloro-bis[chloro-(η⁵-pentamethylcyclopentadienyl)rhodium(III)] with the stoichiometric amounts of 1 and 8 yielded the corresponding mononuclear complexes with P-monodentate ligands: [RhC₂(η⁵-C₅Me₅)(L-κP)], 9 and 10, respectively. Attempted deprotonation of 9 with LiBu or KOt-Bu gave intractable mixtures, in which the parent complex 9 as the major component was accompanied by two new compounds, likely the diastereoizomeric phosphinocarboxylate complexes. A defined O,P-chelating phosphinocarboxylate complex, [SP-4-2]-carbonyl-[rac-2-{(diphenylphosphino)methyl}ferrocenecarboxylato-κ²O,P]-tricyclohexylphosphinerhodium(I) (12), was obtained from the displacement of acetylacetonate(1−) (acac) ligand in [Rh(acac)(CO)(PCy₃)] (Cy = cyclohexyl) with acid 1. The structures of 1, 6 · CHCl₃, and 7 · 1/2 CH₂Cl₂, 10, and hydrated complexes 9 and 12 were determined by single-crystal X-ray diffraction.     

Fluorinated Heterobutadienes/Trimethylphosphine: A Reactivity Study

The reactions of fluorinated heterobutadienes F 2 C=X--C(R)=Y (X = N, CH; Y = O, N-Mes; R = Ph, t-Bu), A-D , with the PMe 3 were studied. In any case, a different reaction pathway was observed, depending on the specific nature of A-D . These reactions lead to some novel organophosphorus species, including P-ylides and u 5 -azaphosphinines. u 5 -phospholenes, as observed with phosphites, for example, were not observed, but with phosphinidine (P--Ph), the heterobutadienes B and C form u 3 -oxazaphospholenes. Therein the complex (Me 3 P) 3 Ni[cyclo-P(Ph)OC(Ph)NC(CF 3 ) 2 ] was obtained and structurally characterized.     

Phosphine-catalyzed formal vinylogous aldol reaction of γ-methyl allenoates with aldehydes: easy access to 1,3-dioxanes and dienols

A phosphine-catalyzed formal vinylogous aldol reaction of γ-methyl allenoates with aldehydes is herein reported, in which the γ-methyl group is directly involved in the carbon–carbon bond formation. Under the catalysis of triarylphosphine (20 mol %) and in the presence of a protic additive, γ-methyl allenoates and aldehydes chemo- and stereoselectively produce functionalized 1,3-dioxanes or dienols in modest to good yields. These chemical transformations provide easy excess to oxy-functionalized enoates and dienoates under very mild conditions.     

Cross-Electrophile C−PIII Coupling of Chlorophosphines with Organic Halides: Photoinduced PIII and Aminoalkyl Radical Generation Enabled by Pnictogen Bonding

Pnictogen bonding (PnB) has gained recognition as an appealing strategy for constructing novel architectures and unlocking new properties. Within the synthetic community, the development of a straightforward and much simpler protocol for cross-electrophile C−P^III coupling remains an ongoing challenge with organic halides. In this study, we present a simple strategy for photoinduced PnB-enabled cross-electrophile C−P^III couplings using readily available chlorophosphines and organic halides via merging single electron transfer (SET) and halogen atom transfer (XAT) processes. In this photomediated transformation, the PnB formed between chlorophosphines and alkyl amines facilitates the photogeneration of P^III radicals and α-aminoalkyl radicals through SET. Subsequently, the resulting α-aminoalkyl radicals activate C−X bonds via XAT, leading to the formation of carbon radicals. This methodology offers operational simplicity and compatibility with both aliphatic and aromatic chlorophosphines and organic halides.