Phosphorus Chemistry Research Articles

Zirconium species as tools in phosphorus chemistry: II [Cp 2ZrMe 2], a useful reagent

The usefulness of dimethylzirconocene [Cp 2ZrMe 2], 1, in phosphorus chemistry is illustrated with several examples. Reactions involving methane evolution allow the synthesis of small rings as well as macrocycles. Methyl group transfer from 1 can be performed with phosphenium salts, or can be realized on the surface of metalladendrimers. The carbozirconation reaction on chlorophosphaimine leads to the first P-metalated iminophosphorane which presents a versatile reactivity.

Transition metal chemistry of phosphorus based ligands. Ruthenium(II) chemistry of bis(phosphino)amines, X 2PN(R)PX 2 (R=H or Ph, X=Ph; R=Ph, X 2=O 2C 6H 4)

Reactions of CpRuCl(PPh 3) 2 with bis(phosphino)amines, X 2PN(R)PX 2 ( 1 R=H, X=Ph; 2 R=X=Ph; 3 R=Ph, X 2=O 2C 6H 4) give neutral or cationic mononuclear complexes depending on the reaction conditions. Reaction of 1 with CpRuCl(PPh 3) 2 gives one neutral complex, [CpRu(Cl)( η 2-Ph 2PN(H)PPh 2)] ( 4) and two cationic complexes, [CpRu( η 2-Ph 2PN(H)PPh 2)( η 1-Ph 2PN(H)PPh 2)]Cl ( 5) and [CpRu(PPh 3)( η 2-Ph 2PN(H)PPh 2)]Cl ( 6), whereas the reaction of 2 with CpRuCl(PPh 3) 2 leads only to the isolation of cationic complex, [CpRu(PPh 3)( η 2-Ph 2PN(Ph)PPh 2)]Cl ( 7). The catechol derivative 3, in a similar reaction, affords an interesting mononuclear complex [CpRu(PPh 3){ η 1-(C 6H 4O 2)PN(Ph)P(O 2H 4C 6)} 2]Cl ( 8) containing two monodentate bis(phosphino)amine ligands. The structural elucidation of the complexes was carried out by elemental analyses, IR and NMR spectroscopic data.

CycloSal-2',3'-dideoxy-2',3'-didehydrothymidine monophosphate (cycloSal-d4TMP): synthesis and antiviral evaluation of a new d4TMP delivery system.

The synthesis, hydrolysis, and antiviral evaluation of novel, lipophilic cycloSal-d4TMP derivatives 3a-h of the anti-HIV dideoxynucleoside 2',3'-dideoxy-2',3'-didehydrothymidine (d4T, 1) are reported. This pro-nucleotide concept has been designed to deliver d4TMP (2) by selective chemical hydrolysis. All compounds 3a-h were synthesized using phosphorus(III) chemistry in good yields and in somewhat lower yields using phosphorus(V) chemistry starting from substituted salicyl alcohols 6a-h. The phosphotriesters 3 were obtained without stereochemical preference with respect to the configuration at the phosphorus center as 1:1 diastereomeric mixtures. However, a few of the triesters 3 could be separated into the diastereomers by means of semipreparative HPLC. In a 1-octanol/phosphate buffer mixture, all compounds 3 exhibited 9-100-fold higher lipophilicity as judged from their Pa values as compared to d4T (1). Furthermore, in hydrolysis studies 3 decomposed under mild aqueous basic conditions releasing solely d4TMP (2) and the diols 6 following the designed tandem reaction sequence. A correlation of the electronic properties introduced by the substituents and the half-lives of triesters 3 was observed. Thus, by varying the substituent, the half-lives of 3 could be adjusted over a wide range of compounds still delivering d4TMP (2) selectively. Phosphotriesters 3 exhibited considerable activity against HIV-1 and HIV-2 in wild-type human T-lymphocyte (CEM/O) cells as well as mutant thymidine kinase-deficient (CEM/TK-) cells. Surprisingly, we observed a 3-80-fold difference in antiviral activity between the two diastereomers. Our data clearly prove that the cycloSal-d4TMPs deliver exclusively the nucleotide d4TMP not only under simulated hydrolysis conditions but also under cellular conditions and thus fulfill the thymidine kinase-bypass premise. Therefore, the cycloSal-nucleotide concept is the first reported pro-nucleotide system that delivers the dideoxynucleotide by a pH-driven, chemically activated, tandem reaction without the requirement of an enzymatic contribution.

Isolation of a benzene valence isomer with one-electron phosphorus-phosphorus bonds

A tetraphosphabenzene analog of the postulated anti-tricyclohexylene, a singlet biradical valence isomer of benzene, has been isolated. The tricyclic derivative features one-electron phosphorus-phosphorus bonds, which result from the pi*-pi* interaction between two diphosphirenyl radicals. Such one-electron bonds may play a wider role in phosphorus chemistry.

The Ene Reaction in the Chemistry of Low-Coordinate Phosphorus

The ene reaction belongs to one of the simplest and most versatile reaction categories in organic chemistry. Recently ene reactions involving compounds of low-coordinate phosphorus, phospha-ene reactions, have found wide application in the synthesis of different classes of organophosphorus compounds. For phospha-ene reactions, four main types are currently known which involve the employment of phosphaalkenes, iminophosphines and phosphaalkynes. Also included are retro-phospha-ene reactions, which reveal access to short-lived and highly reactive phosphaalkenes. The experimentally observed regiochemistry is in agreement with MO calculations, carried out on the simplest parent reactions of type I - IV.

ChemInform Abstract: (Cp2ZrHCl)n, a Useful Reducing Agent in Phosphorus Chemistry.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synthesis and Crystal Structure of Phosphorus(V) Nitride α‐P3N5

A varied chemistry of ternary and higher phosphorus(v) nitrides has developed during the last few years. However, the crystal structure of the binary nitride P3N5 has proved elusive until now. The network structure built up by PN4 tetrahedra (depicted' on the right) resembles that of SiO2 and Si3N4. Surprisingly, in α-P3N5 the PN4 tetrahedra are also connected through edge-sharing.

The Origins of Life: What One Needs to Know

Many solar systems in the universe may be expected to contain rocky planets that have accreted organic compounds. These compounds are likely to be universally found. In addition, the chemistry of sulfur, phosphorus, and iron is likely to dominate energy transductions and monomer activation, leading to the eventual emergence of polymers. Proteins and polynucleotides provide living matter with function, structure, and information. The conceptual puzzle regarding their emergence is discussed. The fitness of various elements to serve various roles is analyzed from the viewpoint of electron orbitals. Elements with d orbitals are of central importance.

Cp 2ZrHCl] n a useful reducing agent in phosphorus chemistry

Selective reductions of PO, PS, >CC<, CO bonds with [Cp 2ZrHCl] n are described, as well as halogen-hydride exchanges.

ChemInform Abstract: The Chemistry of Phosphorus. Part 239. Reaction of Diphosphane(4) with Diborane(6) and with THF‐Borane: Formation of Diphosphane‐borane, P2H4. times.BH3, and Diphosphane‐1,2‐bis(borane), BH3×P2H4×BH3.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Another Exciting Chapter in Phosphorus Chemistry. Ylidic Four‐Membered Rings with Four π‐Electrons

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Trends in gear oil additives

AbstractOf the total amount of additives produced and sold in the world, gear oil additives are the second largest group, after the engine oil additives. According to the purpose of the finished lubricant, these additives can be classed as either additives for automotive gear lubricants or additives for industrial gear lubricants. Although the main function of such additives is the same for both types of lubricants, namely to reduce friction and wear and avoid surface fatigue, permanent deformation of the tooth, and excessive wear, the requirements that these lubricants have to meet are different. The most important specifications for automotive gear lubricants are, in the USA, API GL‐1—GL‐6, and MIL L 2105 A—2105 D, respectively, whereas in Europe manufacturers tend to have taken GL‐4 or GL‐5 as a basis, and added their own supplementary requirements. Industrial gear lubricants are manufactured according to US Steel 224 specification, DIN 51517/3, and AGMA 250.04. The gear oil additives themselves are based on sulphur and phosphorus chemistry, but other chemicals are introduced into the additive packages to ensure oxidation stability, anti‐corrosion protection, copper compatibility and better seal compatibility. Boron compounds are shown to improve the antiwear and extreme‐pressure properties of the lubricants, as well as oxidation stability, thermal stability and detergency. Rig and bench tests demonstrate the benefits of adding boron compounds to fully formulated GL 5 oils and to classic sulphur‐phosphorus additive packages for automotive and industrial gear oils.

Prebiotic phosphorus chemistry reconsidered.

The available evidence indicates that the origin of life on Earth certainly occurred earlier than 3.5 billion years ago and perhaps substantially earlier. The time available for the chemical evolution which must have preceded this event is more difficult to estimate. Both endogenic and exogenic contributions to chemical evolution have been considered; i.e., from chemical reactions in a primitive atmosphere, or by introduction in the interiors of comets and/or meteorites. It is argued, however, that the phosphorus chemistry of Earth's earliest hydrosphere, whether primarily exogenic or endogenic in origin, was most likely dominated by compounds less oxidized than phosphoric acid and its esters. A scenario is presented for the early production of a suite of reactive phosphonic acid derivatives, the properties of which may have foreshadowed the later appearance of biophosphates.

Ylidic Four‐Membered Rings with Four π‐Electrons—Another Exciting Chapter in Phosphorus Chemistry

Ylidic Four‐Membered Rings with Four π‐Electrons—Another Exciting Chapter in Phosphorus Chemistry

ChemInform Abstract: Zirconium Species as Tools in Phosphorus Chemistry. Part 1. (Cp2ZrHCl) n, a Versatile Reagent

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Phosphorus 31 solid state NMR characterization of oligonucleotides covalently bound to a solid support.

31P cross polarization (CP) magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectra were acquired for various linear and branched di- and tri-nucleotides attached to a controlled pore glass (CPG) solid support. The technique readily distinguishes the oxidation state of the phosphorus atom (phosphate versus phosphate), the presence or absence of a protecting group attached directly to phosphorus (cyanoethyl), and other large changes in the phosphorus chemistry (phosphate versus phosphorothioate). However, differences in configurational details remote from the phosphorus atom, such as the attachment position of the ribose sugar (2'5' versus 3'5'), or the particulars of the nucleotide bases (adenine versus uridine versus thymine), could not be resolved. When different stages of the oligonucleotide synthetic cycle were examined, 31P CPMAS NMR revealed that the cyanoethyl protecting group is removed during the course of chain assembly.

Rings and cages containing phosphorus, arsenic and antimony-new chemistry

Rings and cages containing phosphorus, arsenic and antimony-new chemistry

A Study of Synthesis and Thermal Properties of Cyclotriphosphazene-Containing Polyimides

Abstract Referring to the field of phosphorus chemistry the fragment N(CN) is discussed as pseudochalcogen.

Making the Most of Inventive Discoveries in the Phosphorus Chemistry Field: Implications of a Probability Model of Invention

Making the Most of Inventive Discoveries in the Phosphorus Chemistry Field: Implications of a Probability Model of Invention

Horizons in Phosphorus Chemistry

Abstract Where has phosphorus chemistry been and where is it going? To answer this question, we must explore current areas of activity, the concentration of research in these areas, and what appears to be trends and emerging areas that might suggest what the future may hold. For this purpose, we shall examine several sources of current research information. These comprise current literature, reviews and overviews, recent symposia and correlative articles. This should place us in a position to learn in which directions phosphorus chemistry may be headed in the 21st century. We must keep in mind that some of the best discoveries leading to new areas of importance result from so called “accidental” discoveries. However, a perceptive mind stimulated by research at the forefront of knowledge is best tuned to seize these opportunities. It is hoped that this discussion will provide insight into our own research and perhaps suggest new and untried approaches. One approach is to examine related chemistries to lear...