Novel Phosphoric Acids

Zhang H (2004) Novel phosphoric acid doped polybenzrmidazole membranes for fuel cells. PhD Thesis, Rensselaer Polytechnic Institute, Troy, NY, December 2004... 

A highly enantioselective kinetic resolution of protected homoaldols via a catalytic asymmetric transacetalization reaction could be achieved with a novel phosphoric acid STRIP (6) (Table 1) [25]. A catalyst loading of 1 mol% could be routinely used at 20°C, and even 0.1 mol% of the catalyst can give very similar enantiomeric ratios. The method is applicable to the resolution of a wide range of secondary and, most remarkably, of tertiary homoaldols. In most cases, both acyclic homoaldols 7 and cyclic homoaldols 8 could be obtained in enantiomeric ratios exceeding 95 5. Although chemical kinetic resolutions of secondary alcohols by other methods are well developed [26], these are not readily applicable to kinetic resolutions of tertiary alcohols [27-34]. 

Pron et al. [246] used novel phosphoric acid diesters to protonate the emeraldine base form of P(ANi) in solvents such as toluene, decaline or m-cresol, yielding solutions of the conductive form of the CP. Solutions of the highly versatile thermoplastic Acrylonitrile-Butadiene-Styrene (ABS) were then mixed with these... 

Antilla et al synthesized a novel phosphoric acid derivative (48), starting from (R)-VAPOL (vaulted biphenanthrol) [181], and demonstrated its catalytic activity in the addition of sulfonamide to aldimines, giving rise to protected aminals, which have been incorporated into peptide chains as retro-inverso peptide mimics. (Scheme 2.105) [182]... 

Wang, X. Xu, C. Golding, B. T. Sadeghi, M. Cao, Y Scott, K., A novel phosphoric acid loaded quaternary l,4-diazabicyclo-[2.2.2]-octane polysulfone membrane for intermediate temperature fuel cells. International Journal of Hydrogen Energy 2011,56(14), 8550-8556. 

When acted upon by phosphorous acid, the polymethylenediamides (60) afford the novel diphosphonic acids (61),53 while lactams are converted into the related compounds (63).64 The pyrrol idonebis(phosphonic acid) (62) is evidently obtained by ring contraction of the acid (61 n = 2).55... 

A novel demonstration of the latent reactivity of the phosphoryl bond and the apparent ease with which the number of ligands around the phosphorus atom can change under very mild conditions is provided by the hydrogen phosphonate (100), prepared from catechol and phosphorous acid or PC13. When treated with DCC,... 

Most notably, the Antilla laboratory has employed VANOL and VAPOL phosphoric acid derivatives in several novel asymmetric transformations. In addition, TADDOL and phosphordiamide phosphoric acid derivatives have been applied in several Mannich-type reactions. 

Lastly, Antilla has disclosed a novel asymmetric desymmetrization of a wide range of aliphatic, aromatic, and heterocyclic meso-aziridines with TMS-N3 promoted by 11 and related 12 (Scheme 5.31) [56]. Uniquely, this is one of only several reports of electrophilic activation of nonimine substrates by a chiral phosphoric acid. Mechanistic studies suggest that silylation of 11 or 12 by displacement of azide generates the active catalytic species A. Consequently, the aziridine is activated through coordination of it carbonyl with chiral silane A to produce intermediate B. Nucleophilic ring opening by azide furnishes the desymmetrized product and regenerates 11 or 12. 

This novel Bronsted acid catalyzes the Diels-Alder reaction between ethyl vinyl ketone and various acycUc siloxy dienes to furnish adducts in uniformly high yields and ee s. Further, the corresponding chiral phosphoric acid was unable to catalyze this reaction. 

An enantioselective Strecker reaction involving Brpnsted acid catalysis uses a BINOL-phosphoric acid, which affords ees up to 93% in hydrocyanations of aromatic aldimines in toluene at -40 °C.67 The asymmetric induction processes in the stereoselective synthesis of both optically active cis- and trans-l-amino-2-hydroxycyclohexane-l -carboxylic acids via a Strecker reaction have been investigated.68 A 2-pyridylsulfonyl group has been used as a novel stereocontroller in a Strecker-type process ees up to 94% are suggested to arise from the ability of a chiral Lewis acid to coordinate to one of the sulfonyl (g)... 

Gumi, T., Oleinikova, M., Palet, C., Valiente, M. and Munoz, M. (2000) Facilitated transport of lead(II) and cadmium(II) through novel activated composite membranes containing di-(2-ethyl-hexyl)phosphoric acid as carrier. Analytica Chimica Acta, 408, 65. 

An enantioselective Friedel-Crafts alkylation of pyrroles with /V-acylimincs has been reported <070L4065>. The reactions were run in the presence of chiral phosphoric acids. A novel C-H bond activation procedure was developed for the preparation of heteroarylamides including pyrrole-3-carboxamides <07CL872>. The reactions involved imine-substituted pyrroles, isocyanate electrophiles, and a rhenium catalyst. 

The investigation of the formation of metastable phosphate phases under hydrothermal conditions has shown the different factors that control synthesis of a specific compound [14]. Among these factors are the molar ratio P Ti in the reaction mixture, the concentration of phosphoric acid and pH. This paper reports the synthesis of a novel layered compound, Ti202H(P04)[(NH4)2P04]2, under mild hydrothermal conditions in the system Ti(IV)-H3P04-(NH2)2C0-H20 and data on its characterization. 

A novel enantioselective synthesis of an antagonist of the NMDA receptor, c/s-perhydroisoquinoline LY235959, was achieved in 13% overall yield and 17 steps from (R)-pantolactone in the laboratory of M.M. Hansen. The phosphoric acid portion of the target was introduced by a high-yielding Arbuzov reaction. 

Biological chemistry and its needs increasingly dominate the phosphorus(v) acids area and the majority of novel results relate to compounds derived from phosphonic and phosphinic, rather than phosphoric acids. Numbers of studies of compounds related to inositol and to carbohydrates continue to appear, although few contain truly novel results. Phosphorus-containing analogues of amino acids... 

Scheme 3.4 Novel structural motifs of chiral phosphoric acid catalysts.

Aminals, compounds having two amino groups bound to the same carbon atom, are represented in many medicinal agents having versatile therapeutic action, such as proteinase inhibitors and neurotensins. Antilla and coworkers developed an en antioselective synthesis of protected aminals from the amidation reaction of N Boc imines with a series of sulfonamides catalyzed by chiral phosphoric acids (Scheme 3.54a) [111]. In this novel enantioselective transformation, phosphoric acid 9 exhibited excellent catalytic activity and enantioselectivity in addition to N Boc aromatic imines. The enantioenriched aminal products were stable upon storage neither decomposition nor racemization was observed in solution over several days. The same research group reported the enantioselective amidation reaction of N Boc aromatic imines with phthalimide or its derivatives (Scheme 3.54b) [112]. 

In 2008, Du and coworkers designed and synthesized novel double axially chiral phosphoric acid catalysts based on BINOL [28]. Subsequently, these catalysts have been successfully applied in asymmetric transfer hydrogenation of 2 substitued (Table 10.8) and 2,3 disubstitued quinolines (Scheme 10.26). They found that ether was the best solvent. For 2 substitued quinolines, up to 98% ee was obtained when the substitutent of catalyst was cyclohexanyl. 

Synthesis.—Comprehensive reviews on glycosyl esters of nucleoside pyrc>-phosphates and teichoic acids have appeared in the past year as have details of the preparation of xylulose-5-phosphate using transketolase. Phosphorylation of glucose by inorganic phosphate in the presence of histidine occurs under simulated primitive earth conditions and the reactive species is probably an iST-phosphorylated histidine. Phosphorylation of sugars by heating them with 100% phosphoric acid in vacuo is a novel experimental... 

Very interesting novel zinc phosphate structures were discovered in the group of Yu and Xu [12] using a combinatorial approach. The setup resembles the one initially described by Akporiaye [5] in that the well are formed in a Teflon block, with each well having a volume of about 800 pi. Product analysis was done with an automated powder XRD setup after the samples had been transferred to a sample holder. Solids were formed from zinc solution, phosphoric acid and N,N -dimelhylpiperazine as precursors. The most interesting material formed was a zinc phosphate with 16-membered ring channels in one direction, but two other structures with smaller pore openings were also described in this publication. 

Polybenzimidazole films doped with phosphoric acid have also been investigated for direct methanol fuel cells. These membranes, however, only display the requisite conductivities at high temperatures and have only been demonstrated in vapor feed systems operated at 150-200 C. Thus, although these novel membrane applications have been demonstrated to have decreased methanol permeability in fuel cells, none of the systems have been successful in being applied to low temperature liquid-feed direct methanol fuel cells. 

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