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PubMed2006

Nucleotides and nucleic acids: a source of inspiration for the development of new, phosphorus-centered functional groups.

Synthetic methodologies aiming at the creation of new phosphorus-centered functional groups are reported, as well as applications to the field of nucleotide chemistry. Thus, difluorophosphonothioate-based, ionic reagents 3b and 3d are shown to allow the stereocontrolled and efficient synthesis of phosphonodifluoromethyl analogues of nucleoside-3'-phosphates. An alternate, radical approach describes the use of hypophosphorous acid to stereoselectively link two furanosyl units in positions 3 and 5, and to provide an access to alpha,alpha-difluoro-H-phosphinates. These intermediates are shown to be precursors to the corresponding fluorinated phosphonic acids, phosphonothioic acids and variously substituted phosphinates.

Nucleic Acids↗
PubMed2003

Nitrogen ligands on phosphorus(III) Lewis acceptors: A versatile new synthetic approach to unusual N-P structural arrangements.

A series of Lewis acid-base adducts of phosphines with amines or pyridines have been prepared and structurally characterized, demonstrating the importance of Lewis acceptor behavior in the chemistry of electron-rich (lone-pair-bearing) centers. The neutral and cationic complexes all contain examples of N-P coordinate bonds that are void of N-P pi-bonding and therefore represent definitive N-P single bonds. The structures are examples of N-P topologies that are rare or have not previously been observed, highlighting the synthetic viability of Lewis acid-base coupling in the still developing field of nitrogen-phosphorus chemistry.

Journal Article↗
PubMed1995

In CA1 hippocampal neurons, the redox state of NMDA receptors determines LTP expressed by NMDA but not by AMPA receptors.

1. Using extracellular recording techniques in the CA1 region of the rat hippocampus, we have evaluated the effects of the redox reagents 5,5O-dithiobis-2-nitrobenzoic acid (DTNB) and tris (carboxyethyl) phosphine (TCEP) on long-term potentiation (LTP) expressed by alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid (AMPA) and N-methyl-D-aspartate (NMDA) receptors. In physiological conditions a high-frequency stimulation (HFS) of Schaffer collateral-commissural fibers induced a LTP expressed by a persistent increase (73 +/- 13%, mean +/- SE, n = 8/10) of AMPA field potentials (LTPA). In the presence of 10 microM of 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and reduced concentration of Mg2+ (0.1 mM) to boost NMDA receptors, the HFS induced LTP of NMDA field potentials (LTPN; 62 +/- 11%, n = 8/10). 2. The thiol-oxidizing reagent DTNB (200 microM) reduced, by 46 +/- 5% (n = 24), NMDA-receptor field potentials (NMDA-FP), and this effect could not be reversed by extensive washing. The disulfide-reducing agent TCEP (200 microM) slightly increased AMPA-FP and reversed the DTNB-induced inhibition of NMDA-FP. 3. DTNB (200 microM, 10 min), and TCEP (200 microM, 20 min), had no effect on AMPA-FP (98 +/- 3% and 101 +/- 5%, respectively, n = 12). 4. DTNB (200 microM, 15 min) did not prevent the induction or expression of LTPA (-12 and -5%, respectively, n = 8/8). Similar results were observed with TCEP (200 microM, 20 min).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2002

Synthesis of hcp-Co Nanodisks.

hcp Co disk-shaped nanocrystals were obtained by rapid decomposition of cobalt carbonyl in the presence of linear amines. Other surfactants, in addition to the amines, like phosphine oxides and oleic acid were used to improve size dispersion, shape control, and nanocrystal stability. Co disks are ferromagnetic in character and they spontaneously self-assemble into long ribbons. X-ray and electron diffraction, electron microscopy, and SQUID magnetometry have been employed to characterize this material.

Amines↗
PubMed2004

New entries in Lewis acid-Lewis base bifunctional asymmetric catalyst: catalytic enantioselective Reissert reaction of pyridine derivatives.

The first catalytic enantioselective Reissert reaction of pyridine derivatives that affords products with excellent regio- and enantioselectivity is described. The key for success is the development of new Lewis acid-Lewis base bifunctional asymmetric catalysts containing an aluminum as a Lewis acid and sulfoxides or phosphine sulfides as a Lewis base. These reactions are useful for the synthesis of a variety of chiral piperidine subunits, and catalytic enantioselective formal synthesis of CP-293,019, a selective D4 receptor antagonist, was achieved. Preliminary mechanistic studies indicated that both sulfoxides and phosphine sulfides can activate TMSCN as a Lewis base. In addition, the sulfoxides with appropriate stereochemistry might stabilize a highly enantioselective bimetallic complex (a presumed active catalyst) through internal coordination to aluminum.

Aluminum↗
PubMed2005

An epidemic of occupational contact dermatitis from an acrylic glue.

Dermatological examinations were performed in 81 workers involved in the manufacture of electric coils for television displays, who had worked for 4 years in contact with a glue containing isobornyl acrylate, acrylic acid, N,N dimethyleneacrylamide, phosphine oxide, bis(2,6-dimethoxybenzoyl) (2,4,4-trimethylpentyl)- and beta-carboxyethyl acrylate. The glue was cured by 350-500-nm ultraviolet and visible radiations. Acrylate-specific dermal lesions were detected in 21 (25.9%) people. Occupational irritant contact dermatitis was diagnosed in 12 (15%) of the workers and occupational allergic contact dermatitis in 9 (11.2%). 12 people reacted to acrylates. Cross-reactions with methacrylates were not observed. The highest number of positive tests was obtained with triethyleneglycol diacrylate (10 people) and diethyleneglycol diacrylate (9), followed by 1,6-hexanediol diacrylate (5), 1,4-butanediol diacrylate (4), beta-carboxyethyl acrylate (3), tripropyleneglycol diacrylate (2) and pentaerythritol triacrylate (2). No cases of allergy to isobornyl acrylate, N,N-methylenebisacrylamide or phosphine oxide were noted.

Acrylates↗
PubMed2005

Hybridization dependent cleavage of internally modified disulfide-peptide nucleic acids.

Selectivity of the cleavage of single stranded over hybridized forms of internally modified disulfide-peptide nucleic acids (PNA) has been optimized using a series of phosphines and thiols, which have different sizes and charges. For the most selective cleaver found (tris-(carboxyethyl)-phosphine), reactivity of single stranded PNA is 33 times higher than that of the PNA-DNA duplex. Selectivity of single stranded disulfide-PNA cleavage has been explained in terms of electrostatic interaction between the substrate and the cleaver.

DNA↗