Phosphoric Acid Derivatives Research Articles

ChemInform Abstract: Electron‐Withdrawing, Biphenyl‐2,2′‐diol‐Based Compounds for Asymmetric Catalysis.

Facile synthetic routes to a chiral chloro-substituted biphenyl-2,2′-diyl hydrogen phosphate and a chiral O,O-biphenyl-2,2′-diyl phosphoramidothioate are described. The performance of these compounds as catalysts for the hydrophosphonylation of imines and the Friedel–Crafts alkylation of indole was investigated. In the latter reaction, the chloro-substituted phosphoric acid derivative was found to rival the best Bronsted acid catalysts reported to date.

(PO→Si) Chelates of Silylmethyl Derivatives of Phosphoric Acids R2P(O)ZCH2SiMe3−nHaln(n= 1−3; Z = O, NMe, CH2, S)

Spatial and electronic structure, 29Si chemical shifts, and the energetics of a wide series of the silylmethyl derivatives of phosphoric acid R2P(O)ZCH2SiMe3−nHaln (Z = O, NR′,CH2, S; R = Me, NMe2, NEt2, OMe, 2R = −NMe(CH2)2NMe−; Hal = Cl, F; n = 1−3) are studied at the MP2 and DFT (B3LYP and B3PW91) levels of theory with different basis sets. The compounds can exist in the noncoordinated (acyclic) form a and the P(O)→Si-coordinated (cyclic) form b. The relative stability of isomers b is determined not only by the degree of the orbital- or charge-controlled O→Si coordination (stabilizing factor) but also by the OPZCSi heterocycle strain energy, Estrain (destabilizing factor). For this reason, only eight of 52 considered molecules exist exclusively in the chelate form b. The results of the NBO and AIM analysis suggest that the optimal combination of the stabilizing and destabilizing factors is achieved for the silylated phosphoramides R2P(O)NR′CH2SiMe3−nHaln. According to the AIM and ELF analysis, relative...

Electron‐Withdrawing, Biphenyl‐2,2′‐diol‐Based Compounds for Asymmetric Catalysis

AbstractFacile synthetic routes to a chiral chloro‐substituted biphenyl‐2,2′‐diyl hydrogen phosphate and a chiral O,O‐biphenyl‐2,2′‐diyl phosphoramidothioate are described. The performance of these compounds as catalysts for the hydrophosphonylation of imines and the Friedel–Crafts alkylation of indole was investigated. In the latter reaction, the chloro‐substituted phosphoric acid derivative was found to rival the best Brønsted acid catalysts reported to date.

DFT Study on the Factors Determining the Enantioselectivity of Friedel−Crafts Reactions of Indole with N-Acyl and N-Tosylimines Catalyzed by BINOL−Phosphoric Acid Derivatives

DFT methods have been used to study the mechanism and the enantioselectivity of the Friedel-Crafts reaction of indoles with acyl and tosyl imides catalyzed by BINOL-phosphoric acid catalysts. The results are in excellent agreement with the experimental enantioselectivities. The energies of the competing transition structures and, thus, the enantioselectivity are rationalized from calculations on a model system. We propose a simple model to predict the absolute configuration of the products.

DFT study of five naphthalimide derivatives: Structures and redox properties

Geometries for five naphthalimide (NI) derivatives proposed as photoactive redox units in cancer treatment, have been optimized in the ground state, reduced and oxidized states using density functional theory (DFT) with the B3LYP hybrid functional and the 6-31G (d,p) basis set. The bond lengths of the N-[3-(dimethylamino)propyl]-1,8-naphthalimide derivative showed the most variation from the other four NI derivatives due to the nature of its substituent. An examination of atomic charges and spin densities shows in general that the ring carbons are most significant, except in the N-(propyl)-1,8-naphthalimide,3′-phosphoric acid derivative, where charges and densities are localized in the phosphate group. Single point energy calculations, both in vacuum and solution were performed for each NI derivative. The adiabatic and vertical electron affinities and ionization potentials are given for each of the NI derivatives in the ground state. The results suggest that none of the five NI derivatives studied can oxidize DNA nucleobases via direct electron transfer from the ground states, and that the dark toxicity of the compounds is thus most likely very low.

Bifunctional Chiral Organocatalysts in Organic Transformations

In continuation to our earlier review, we report herein further development on the organocatalytic approach for the synthesis of enantioenriched organic compounds. Application of synthetic bifunctional chiral organocatalysts with emphasis on Bronsted acid catalyst derived from chiral phosphoric acid derivative, and mechanism of asymmetric catalysis are discussed.

Extraction of cadmium from dilute solution using supported liquid membrane

The extraction efficiencies of three phosphoric acid derivatives (D2EHPA, PC-88A and Cyanex 272) for Cd in supported liquid membrane (SLM) have been reported. The equilibrium study indicated the release of two moles of H + ions from the extractant for extraction of one mole of cadmium ion and association of two moles of the extractants in the extracted species in each case. The diffusion constant of Cd–D2EHPA, Cd–PC-88A and Cd–Cyanex 272 complex through the membrane phase was found to be 2.53 × 10 −9, 5.435 × 10 −9 and 11.22 × 10 −9 m 2/s, respectively. The effects of various parameters such as flow rate, pH of feed solution, concentration of extractants in membrane phase, concentration of H 2SO 4 in strip solution and concentration of Cd in feed solution on cadmium flux ( J Cd) have been investigated. At pH 7.5, the percentage of cadmium extraction was found to be maximum with 600 mol/m 3 D2EHPA and PC-88A and 800 mol/m 3 Cyanex 272. The extraction of cadmium using the phosphoric acid derivative follows the order D2EHPA > PC-88A > Cyanex 272.

Enantioselective Extraction of Racemic Mandelic Acid by Di(2‐ethylhexyl) Phosphoric Acid and Tartaric Acid Derivatives as Mixed Complex Chiral Selectors

The distribution behavior of mandelic acid (MA) enantiomers was examined in a two‐phase system containing di(2‐ethylhexyl) phosphoric acid (D2EHPA) with two tartaric acid derivatives as complex chiral selectors in n‐octanol. Factors affecting the extraction were investigated, including the structure and concentration of tartaric acid as well as the concentration of D2EHPA and D,L‐MA. The results showed that both the distribution ratio and enantioselectivity were greatly improved by using a complex chiral selector rather than using the tartaric acid derivative by itself. Finally, it was found that the formation of mixed complex chiral selectors by mixing two tartaric acid derivatives with D2EHPA can improve the capacity of enantioselective extraction.

Synthesis of acetal and phosphocyclic methriolipids

The first representatives of acetal and phosphocyclic lipids based on methriol (2-hydroxymethyl-2-methyl-1,3-propanediol) were synthesized. The interaction of the starting triol with higher aldehydes gave the corresponding alkylidene compounds, which were subsequently phosphorylated by derivatives of phosphorous acid. The intermediate amidophosphites were treated without isolation with iodobenzene, sulfur, or selenium to give phosphoacetals and their thio- and selenoanalogues, which are acetal phospholipids. Methriol bicyclophosphite was also used in the lipid synthesis. It was acylated with palmitoyl chloride at one of the bicyclic oxygen atoms. Alcoholysis of acyl polyol chlorophosphite resulted in a phospholipid, which was oxidized with sulfur to give thionphosphate.

A 31P CP/MAS NMR study of PbS surface [formula omitted]-dialkyldithiophosphate lead(II) complexes

31P CP/MAS NMR spectroscopy was used to study the adsorption of six different O , O ′ -dialkyldithiophosphate ions on the surface of synthetic galena (PbS). The 31P CP/MAS NMR spectra of the surface lead(II) dithiophosphates were compared with the 31P CP/MAS NMR spectra of polycrystalline lead(II) dithiophosphate complexes of the same ligands. Surface complexation of the dialkyldithiophosphate ions was established on the surface of PbS. A terminal S , S ′ -chelating coordination is suggested for the surface complexes. The bulkier alkyl groups lead to surface precipitation in addition to the surface adsorption. Derivatives of monothiophosphoric and phosphoric acids were displayed as hydrolysis products of dialkyldithiophosphates on the synthetic PbS, the amount of which depends on the type of alkyl group.

Reaction of thio and seleno phosphoric acid derivatives with O‐thioacylated hydroxylamine

AbstractThe reactivity of thio and seleno analogs of phosphoric acid 1b–f with O‐thioacylhydroxylamine 2 was examined. The experimental evidence for the proposed mechanism involving an N—O bond cleavage and a single electron transfer process (SET) from phosphate anions was collected. The influence of phosphoric acids 1 structure and their oxidation potentials on the course of the reaction and products 3, 4, 6, 7 distribution was presented. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:767–773, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20368

New promoters for the molybdenum hexacarbonyl- mediated Pauson–Khand reaction

A systematic study of new additives for the stoichiometric molybdenum hexacarbonyl- mediated Pauson-Khand reaction resulted in the discovery of several active compounds such as tetra- substituted thioureas, ester and amide derivatives of phosphoric acid, quaternary ammonium bromides and phosphine oxides. Tributylphosphine oxide (TBPO) was the most efficient additive providing PK products in moderate to good yields. Some experimental evidences were found which support a non-oxidative Mo(CO)6 activation by TBPO.

Thermochemical characteristics of phosphorous acid derivatives

Enthalpies of formation enthalpies of a series of phosphorous acid derivatives were estimated from the heat effects of their reactions. The collected thermochemical data was used to analyze, on the basis of the additive scheme, the experimental enthalpies of formation and vaporization of four-coordinate phosphorus derivatives.

Nano-composite of Phosphoric Acid Derivative of Fullerene with SiO2 and its Proton Conductivity

The nano-composite of the phosphoric acid derivative of fullerene ([PO(OH)2]2CC60) with SiO2 was synthesized using the in-situ reaction from [PO(OH)2]2CC60 with tetraethoxysilane (TEOS). The nano-composite was characterized using FT-IR measurements, and its morphology was observed using SEM. The humidity dependence of their proton conductivity for both [PO(OH)2]2CC60 and its nano-composite was investigated. The proton conductivity of the nano-composite is increased more than one order of magnitude higher than that of [PO(OH)2]2CC60 under low relative humidity. This is probably because the more proton conductive sites are generated by SiO2. However its proton conductivity is lower in the humidity range above 60%, probably because the number of the highly dissociative protons from phosphoric acid is decreased after being combined with silica.

Enantioseparation of amino acids by co-extractants with di(2-ethylhexyl)phosphoric acid and tartaric acid derivatives

A co-extraction method using di(2-ethylhexyl)phosphoric acid (D2EHPA) with each of the two tartaric acid derivatives, O, O′-dibenzoyl-(2 S,3 S)-tartaric acid [(+)-DBTA] and O, O′-dibenzoyl-(2 S,3 S)-4-toluoyl-tartaric acid [(+)-DTTA] was developed for the enantioseparation of four amino acids: racemic tryptophan ( rac-Trp), racemic phenylalanine ( rac-Phe), racemic p-hydroxyphenylglycine ( rac-Hpg) and racemic tyrosine ( rac-Tyr). The extractants were prepared in various proportions and diluted in n-octanol. The influence of the extractant composition, concentration of amino acid enantiomers, molecular structure of the solutes and extractive equilibrium temperature were studied. The maximum enantioselectivities of the four amino acids were 4.02, 1.37, 1.52 and 2.06 for Trp, Phe, Hpg and Tyr, respectively. The effects of the molecular structure of the solutes and amino acids along with the equilibrium temperature on the distribution ratio and enantioselectivity were examined, which is helpful for optimizing the extraction systems and realize the large-scale production of pure enantiomer.

Phosphoric Acid Catalyzed Enantioselective Reductive Amination

An efficient and highly enantioselective, organocatalytic reductive amination is described. This reaction proceeds under simple and mild conditions and is catalyzed by phosphoric acid derivative 1. It is assumed to proceed via protonation of the in situ generated ketimine, which undergoes reduction in the presence of commercially available Hantzsch ester 2. The simple fragment coupling works with a wide range of aryl-alkyl or alkyl-alkyl ketones in combination with aryl or heterocyclic amines.

Chiral Brønsted Acid Catalyzed Enantioselective Hydrophosphonylation of Imines: Asymmetric Synthesis of α-Amino Phosphonates

[reaction: see text] A cyclic phosphoric acid derivative, derived from (R)-BINOL, was used as a chiral Brønsted acid (10 mol %) in hydrophosphonylation of aldimines with diisopropyl phosphite at room temperature. Alpha-amino phosphonates were obtained with good to high enantioselectivities.

Chiral Phosphites as Ligands in Asymmetric Metal Complex Catalysis and Synthesis of Coordination Compounds.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Chiral Brønsted acid-catalyzed direct Mannich reactions via electrophilic activation.

It was found that the phosphoric acid derivatives of general structure 1 serve as highly effective catalysts for the direct addition of acetyl acetone to N-Boc-protected arylimines. The beneficial effects of the 3,3'-bisaryl substituents of the catalysts on the enantioselectivity are greatly appreciated, and thus 1d functions as an excellent catalyst. The Brønsted acid-catalyzed direct Mannich reactions presented herein provide an attractive way to construct beta-aminoketones under extremely mild conditions. The stereochemical course of this reaction was established through the synthesis of Boc-(S)-phenylglycine methylester. The transformation thus demonstrated is applicable to a useful method for the synthesis of various phenylglycine derivatives.

Evaluation of water washes for the removal of organophosphorus pesticides from Maine wild blueberries.

Organophosphate pesticides (OPs) are derivatives of phosphoric acid with a basic structure shown in Figure 1. The majority of OPs are insecticides and have been used extensively in agriculture, commercial and residential applications since the late 1970’s, when organochlorine pesticides began to fall out of favor (Organophosphate Fact Sheet, 1996). Although the use of carbamate insecticides has grown dramatically throughout the past decade, the OPs continue to be insect control staples, with worldwide sales topping $2.9 billion in 1992 (Agrow, 1994). The organophosphates tend to be much more toxic to vertebrate populations, but are also as effective and much less expensive than the carbamate class of insecticides.