Diphenylphosphane Oxide Research Articles

S-Block Metal Base-Catalyzed Synthesis of Sterically Encumbered Derivatives of Ethane-1,2-diyl-bis(diphenylphosphane oxide) (dppeO2)

s-Block Metal Base-Catalyzed Synthesis of Sterically Encumbered Derivatives of Ethane-1,2-diyl-bis(diphenylphosphane oxide) (dppeO₂)

Synthesis of 3,4-Disubstituted Pyrroline Nitroxides Containing Diphenylphosphane or Diphenylphosphane Oxide Substituents

Abstract(Methyl 4-(diphenylphosphoryl)-2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrole-3-carboxylate-1-yl)oxydanyl was obtained as a key intermediate of the reaction starting from 3,4-dibromo-2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrol-1-yloxydanyl or (methyl 2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrole-3-carboxylate-1-yl)oxidanyl. This key compound could be converted into an azido-specific Staudinger ligation-inducing spin label, amino- and thiol-specific spin label, or MITO-CP-like antiproliferative agent.

Synthesis and Characterisation of Novel Bis(diphenylphosphane oxide)methanidoytterbium(III) Complexes.

Reaction of [YbCp2(dme)] (Cp = cyclopentadienyl, dme = 1,2 dimethoxyethane) with bis(diphenylphosphano)methane dioxide (H2dppmO2) leads to deprotonation of the ligand H2dppmO2 and oxidation of ytterbium, forming an extremely air-sensitive product, [YbIII(HdppmO2)3] (1), a six-coordinate complex with three chelating (OPCHPO) HdppmO2 ligands. Complex 1 was also obtained by a redox transmetallation/protolysis synthesis from metallic ytterbium, Hg(C6F5)2, and H2dppmO2. In a further preparation, the reaction of [Yb(C6F5)2] with H2dppmO2, not only yielded compound 1, but also gave a remarkable tetranuclear cage, [Yb4(µ-HdppmO2)6(µ-F)6] (2) containing two [Yb(µ-F)]2 rhombic units linked by two fluoride ligands and the tetranuclear unit is encapsulated by six bridging HdppmO2 donors. The fluoride ligands of the cage result from C-F activation of pentafluorobenzene and concomitant formation of p-H2C6F4 and m-H2C6F4, the last being an unexpected product.

Diethyl (iodoethynyl)phosphonate and (iodoethynyl)diphenylphosphane oxide: crystal structures and some cycloaddition reactions

Abstract The title compounds are difunctionalized acetylenic building blocks, which can serve as electrophilic dienophiles and dipolarophiles in [4+2] and azide-iodoalkyne [3+2] cycloaddition reactions, which, however, require strong thermal activation. In their crystal structures, they are self-complementary tectons, which are arranged in polymeric chains maintained by very short intermolecular Csp–I···O=P halogen bonds.

Alkali Metal Catalysed Double Hydrophosphorylation of Nitriles and Alkynes

Catalytic C–P and N–P bond formation via double hydrophosphorylation of nitriles with diphenylphosphane oxide using alkali metal precatalyst [MN(SiMe3)2] (M = Li, Na, K) is reported. The potassium congener was observed to be the most efficient catalyst for converting aryl nitriles to the corresponding N‐((diphenyl‐phosphoryl)(aryl)methyl)‐P,P‐diphenylphosphinic amide [ArCHP(O)‐Ph2NHP(O)Ph2] at mild temperature (60 °C) and with neat reactants. Double hydrophosphorylation of alkynes with HP(O)Ph2 is also very effective when [KN(SiMe3)2] is used as a precatalyst at room temperature and gives the corresponding 1,2‐diylbis(diphenyl‐phosphane oxide [RCHP(O)Ph2CH2P(O)Ph2] as the product. A wider substrate scope of both reactions is explored.

Crystal Structure and Computational Analysis of a Two-Dimensional Coordination Polymer, BiI3(DppeO2)3/2

Catena-poly[fac-triiodobismuth(III)-tris-(µ-ethane-1,2-diylbis(diphenylphosphane oxide-κ2O,O′))], a 2-D sheet network of BiI3 was synthesized from BiI3 and ethane-1,2-diylbis(diphenylphosphane oxide) (DppeO2) in tetrahydrofuran. The crystal structure revealed a trigonal structure with three-fold symmetry at Bi. Bismuth centers show fac-BiI3O3 coordination, with Bi–I = 2.9416(2) A and Bi–O = 2.4583(17) A. The I–Bi–I and O–Bi–O angles (95.520(7)° and 79.04(6)°, respectively) indicate trigonal distortion in the Bi octahedron. Bridging DppeO2 ligands centered on inversion centers give rise to a 2-D sheet polymer. The 8.3 A thick sheets consist of three layers in a sandwich structure. The outer layers are composed of phenyl rings and BiI3 groups with the iodide atoms pointing outward. The central layer consists of the O=PCH2CH2P=O bridging groups. Computational results suggest that semi-conducting behavior arises from Bi(III) centers. A halide to DppeO2 π* transition is suggested by theoretical results.

A Zwitterionic Gold(I) Diphenylphosphane Oxide Complex Stabilized by a Hard Pulling Lewis Acid and a Soft Pushing Lewis Base

The reaction of Ph2P(O)H with B(C6F5)3 provided the Lewis pair complex Ph2(H)POB(C6F5)3 (5) containing a bipolar +P–O–B– linkage. The reaction of 5 with [(tht)AuCl] (tht = tetrahydrothiophene) proceeded with elimination of HCl and formation of [{(C6F5)3BOPPh2}Au(tht)] (6), which can be regarded as push–pull complex between a zwitterionic OPPh2Au unit and a hard Lewis acid, B(C6F5)3, coordinating at the oxygen atom, and a soft Lewis base, tht, coordinating at the gold atom.

Potassium-Mediated Hydrophosphorylation of Heterocumulenes with Diarylphosphane Oxide and Sulfide.

The preparation of the hydrophosphorylation catalysts succeeds via the metalation of dimesitylphosphane oxide and diphenylphosphane sulfide with potassium hydride in ethereal solvents such as tetrahydropyran (THP) and tetrahydrofuran (THF) yielding the tetramers [(thp)K(OPMes2)]4 (1a) and [(thf)3{K(OPMes2)}4] (1b) as well as [(thp)KSPPh2]∞ (2) with a strand-like structure in the crystalline state. In ethereal solution these complexes very slowly degrade into KPAr2 and KE2PAr2 (E = O, S). The catalytic conversion of iPr-N═C═E' (E' = O, S) and of R-N═C═N-R (R = iPr, cHex) to the addition products Ar2P(E)-C(=E')-NHR (Ar = Ph, Mes; E = O, S; E' = O, S, NR) was studied in the presence of catalytic amounts of Ar2PEK (Ar = Ph, Mes; E = O, S). Steric hindrance prevents the addition of dimesitylphosphane oxide to N,N'-diisopropylcarbodiimide, whereas diphenylphosphane oxide and sulfide smoothly add to iPr-N═C═N-iPr yielding Ph2P(E)-C(═N-iPr)-NHiPr (E = O, S).

ChemInform Abstract: Calcium‐Mediated Hydrophosphorylation of Organic Isocyanates with Diphenylphosphane Oxide.

AbstractThe reaction of diphenylphosphane oxide (I) with isocyanates (II) and isothiocyanates (IV) in the presence of a calcium catalyst leads to desired formamides (III) and thioformamides (V), respectively.

Calcium-mediated Hydrophosphorylation of Organic Isocyanates with Diphenylphosphane Oxide

The calcium-mediated addition of diphenylphosphane oxide to organic isocyanates and isothiocyanates yields N-alkyl and N-aryl substituted diphenylphosphorylformamides (E = O, R = iPr, tBu, cHex, Ph, C6H4-4-Br, C6H2-2,4,6-Me3, and Naph) and -thioformamides (E = S, R = iPr, cHex, Ph, and C6H4-4-Me), respectively, of the type Ph2P(O)–C(E)–N(H)R. All derivatives were characterized by IR and NMR spectroscopy as well as X-ray diffraction experiments. The wavenumbers of the N–H stretching modes are smaller for the thio analogues and N-aryl substituents. In the solid state all formamides and thioformamides form dimers by N–H⋯O–P hydrogen bridges. The P–CCE bonds are significantly elongated compared with the P–CPh distances.

Regiospecific Calcium‐Mediated Intermolecular Hydrophosphanylation of Butadiynes with Diphenylphosphane Oxide

AbstractCalcium‐mediated hydrophosphanylation of diphenyl‐ and di(tert‐butyl)butadiyne (2,2,7,7‐tetramethyl‐3,5‐octadiyne) with diphenylphosphane oxide yields 1,4‐diphenyl‐1,3‐butadiene‐2,3‐bis(diphenylphosphane oxide) and 2,2,7,7‐tetramethyl‐4‐octyne‐3,6‐bis(diphenylphosphane oxide), respectively. Alternatively, 1,4‐diphenylphosphanyl‐substituted 1,4‐butadienes are quantitatively oxidized by H2O2 to the corresponding 1,3‐butadiene‐1,4‐bis(diphenylphosphane oxides).

Preparation of Chiral Multifunctional Thiourea–Phosphanes and Synthesis of Chiral Allylic Phosphites and Phosphane Oxides through Asymmetric Allylic Substitution Reactions of Morita–Baylis–Hillman Carbonates

AbstractWe developed a synthetic method to prepare chiral multifunctional thiourea–phosphane catalysts for the asymmetric allylic substitution reaction of Morita–Baylis–Hillman carbonates with diphenyl phosphite or diphenylphosphane oxide to give allylic phosphites and allylic phosphane oxides in high yields with excellent enantioselectivity.

Asymmetric Organocatalytic Conjugate Addition of Diarylphosphane Oxides to Chalcones

AbstractThe first example of a convenient and enantioselective asymmetric conjugate addition of diarylphosphane oxides to chalcones is reported. By using commercially available dihydroquinine as the organocatalyst and diphenylphosphane oxide as the nucleophile, the adducts were isolated in high yield and up to 89 % ee. The final adducts can be easily recrystallized to enantiopure material.

Highly Selective Synthesis of [(Z)‐3‐Chloro‐2‐(phenylselanyl)‐1‐alkenyl]phosphonates and 2‐Ethoxy‐4‐(phenylselanyl)‐2,5‐dihydro‐1,2‐oxaphosphole 2‐Oxides by Electrophilic Reaction of 1,2‐Alkadienylphosphonates with PhSeCl

AbstractThe reactions of monosubstituted 1,2‐alkadienylphosphonates with PhSeCl in THF or dioxane/H2O (10:1) at 70 °C afforded the selenochlorination products [(Z)‐3‐chloro‐2‐(phenylselanyl)‐1‐alkenyl]phosphonates with very high chemo‐ and stereoselectivity, whereas the same reaction with di‐ and trisubstituted allenylphosphonates afforded 2‐ethoxy‐4‐(phenylselanyl)‐2,5‐dihydro‐1,2‐oxaphosphole 2‐oxides exclusively. It was interesting to note that the stereoselctivity for the selenochlorination reaction is opposite to that of the iodo‐ and selenohydroxylation reactions of (allenyl)diphenylphosphane oxides with Cl– acting as the nucleophile. The stereoselectivity of the cyclization reaction is clearly different from that of the selenochlorination reaction.

Small and Versatile – Formyl Anion and Dianion Equivalents

AbstractThis account provides a short overview of the synthetically important class of formyl anions and the less studied formyl dianion equivalents. A brief literature survey, which particularly focusses on asymmetric homologation strategies, is complemented by a detailed description of lithiated (dimethoxymethyl)diphenylphosphane oxide, which is an ideal formyl anion equivalent in reactions with aldehydes. Under acidic conditions the intermediate ketene O,O‐acetals afford homologated carboxylic esters whereas asymmetric dihydroxylation of ketene acetals leads to collapse of the intermediate diols furnishing the corresponding α‐hydroxy carboxylic esters with high stereocontrol. Additionally, it is demonstrated that the silyl‐substituted carbanion may be looked upon as a latent dianion that can react either with two electrophiles or with bis‐electrophiles, the latter transformation yielding ring‐closure coproducts. It is advantageous if the electrophiles are epoxides or epoxides carrying a remote leaving group. The carbanion will ring‐open the epoxide and allow a C→O silyl shift, thus generating the new carbanion. This then reacts with the second electrophile, either inter‐ or intramolecularly. The versatility of these two formyl anion equivalents is demonstrated by selected examples from natural product synthesis.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Synthesis, Structures, and Properties of meso‐Phosphorylporphyrins: Self‐Organization through P–Oxo–Zinc Coordination

The synthesis, structures, and optical and electrochemical properties of meso-phosphorylporphyrins are described. The copper-catalyzed carbon-phosphorus cross-coupling reaction of a meso-iodoporphyrin with di-n-butyl phosphite and diphenylphosphane oxide has proved to be an efficient and general method for the synthesis of meso-phosphorylporphyrins. Zinc phosphorylporphyrins thus obtained readily undergo self-organization through P-oxo-Zn coordination to form noncovalently linked, cofacial porphyrin dimers or linear oligomers, which have been characterized by spectroscopic methods and X-ray crystallographic analyses. In toluene, CH(2)Cl(2), and CHCl(3), the zinc phosphorylporphyrins exist mostly as dimers or monomers, depending on their concentrations, the temperature, and the presence of additives. The self-association constants for dimerization in toluene have been determined by UV/Vis absorption titration measurements. The meso-diphenylphosphorylporphyrin dimer displays excitonic coupling of the Soret band with a splitting energy of 940 cm(-1). Fluorescence lifetimes of the zinc phosphorylporphyrins have been found to be affected only slightly by the concentration of the solution, and by the addition of triphenylphosphane oxide, suggesting that the effect of dimerization on their photodynamics in the S(1) state is negligible. On the other hand, the effect of dimerization is clearly reflected in their electrochemical oxidation processes, as the initially produced radical cations are efficiently delocalized over the two porphyrin rings. These findings demonstrate the potential utility of meso-phosphorylporphyrins as new models for the special pair in photosynthesis and as new building blocks for porphyrin-based supramolecular materials.

The Abnormal Behavior of an Atropisomer: 3,3′‐Dibromo‐1,1′‐difluoro‐2,2′‐binaphthyl Reacting with Alkyllithium Compounds

Abstract1‐Fluoro‐2‐(triethylsilyl)naphthalene (1) and other 1‐fluoronaphthalenes bearing a metalation‐resistant substituent at the 2‐position proved to be totally inert toward base attack. 3‐Bromo‐1‐fluoronaphthalene (6), readily prepared from the 2‐bromo isomer 5 by deprotonation‐triggered heavy halogen migration, was converted into 3,3′‐dibromo‐1,1′‐difluoro‐2,2′‐binaphthyl (8) by consecutive treatment with lithium diisopropylamide, copper(II) bromide and nitrobenzene. The dilithiated intermediate generated from the atropisomer 8 by treatment with 2 equiv. of butyllithium reacted with a variety of electrophiles to afford products such as the diacid 12 or the bis(phosphanes) 14 and 15 in high yields. The latter compound was also obtained in a straightforward manner from (4‐fluoro‐2‐naphthyl)diphenylphosphane oxide (16). Unexpectedly, neither the 3,3′‐dibromobinaphthyl 8 nor its 3,3′‐diiodo analogue 18 were amenable to a unilateral but only to a double‐sided halogen/metal permutation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Acylation of Alkyl Halides and Amino Aldehydes with a Phosphane Oxide‐Based d1‐Synthon

AbstractAlkyl iodides and α‐amino aldehydes can be homologated to the corresponding methyl esters and β‐amino methyl esters, including β‐amino‐α‐hydroxy methyl esters, using lithiated (dimethoxymethyl)diphenylphosphane oxide. The primary α,α‐(dimethoxy)diphenylphosphane oxides obtained by this Horner−Wittig type process collapse to give the target esters under proton‐catalyzed conditions in the presence of water. Detailed and carefully conducted mechanistic studies revealed that the diphenylphosphane oxide group is activated by protonation, and acts as the initial leaving group in this process. In the cases of adducts derived from the reaction of the phosphane oxide‐stabilized anion with α‐amino aldehydes, homologation to the β‐amino‐ and β‐amino‐α‐hydroxy methyl esters can be achieved by KOtBu‐mediated elimination to the intermediate O,O‐ketene acetals. These may either be allowed to react with water under acidic conditions to yield the β‐amino methyl esters, or may be treated under the Sharpless asymmetric dihydroxylation conditions to directly furnish the β‐amino‐α‐hydroxy methyl esters. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Synthesis and Reactions of (2,2,2‐Trifluoroethyl)triphenylphosphonium Trifluoromethanesulfonate.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Studies on an Oxidative 1,4‐Addition to s‐trans‐1,3‐Dienes, a Key Reaction in a Strigol Total Synthesis

AbstractOxidation of 4,6‐heptadienoic acid systems with hydrogen peroxide in the presence of a catalytic amount of diphenyl diselenide leads to 5‐(3‐hydroxypropenyl)dihydrofuran‐2‐one systems with defined relative configuration at the 4 and 7 positions (carboxylic acid numbering). A system having a six‐membered ring as part of the s‐trans‐diene system was an intermediate in a strigol total synthesis; a second system lacking the six‐membered ring is the subject of the present publication. We accomplished a stereoselective synthesis of the diene system by (i) trapping a π‐allyl palladium complex with lithium diphenylphosphinite to give an allylic diphenylphosphane oxide and (ii) a subsequent Horner−Wittig reaction. The species that brings about the oxidative 1,4‐addition is benzeneperoxyseleninic acid. We also report observations that shed some light on the mechanism. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)