Simple method for the introduction of iodo-label on (3-trifluoromethyl) phenyldiazirine for photoaffinity labeling

A simple and mild method was developed for the introduction of iodo-label on (3-trifluoromethyl) phenyldiazirine (TPD) aromatic ring in the presence of three membered diazirine ring. An iodination protocol, I₂-BTI in CH₃CN, was found to be effective even though affinity ligands are pre-installed.     

Simple synthesis of deuterium and 13C labeled trifluoromethyl phenyldiazirine derivatives as stable isotope tags for mass spectrometry

The synthesis of trifluoromethyl diazirine with a stable isotope tag is reported. We found that both Friedel-Crafts acylation and reduction of aryl carbonyl to methylene, using commercially available stable-isotope reagents, were utilized for the synthesis of diazirinyl fatty acid derivatives. The stable isotope labeled diazirine may be valuable for identifying binding sites by mass spectrometry.     

Simple and versatile methods for the fabrication of arrays of live mammalian cells

Single-step methods for the generation of patterned surfaces on hydrogels are presented. Poly(vinyl alcohol) films covalently bonded on glass cover slips and commercially available hydrogel-coated polystyrene plates were used as cell-repellent surfaces. Cell-adhesive domains were created by spotting dilute solutions of sodium hypochlorite onto the surfaces. Alternatively, domains supporting cell attachment were created by exposure to UV light from a xenon excimer lamp, employing a contact mask. Rat skeletal myoblast cells, HEK 293 human embryonic kidney cells and Caco-2 colon carcinoma cells adhered and spread exclusively on modified areas. The surfaces are durable for weeks under cell culture conditions and re-usable after removal of the cells by trypsin treatment. Arrays of adhesive spots seeded with cells at a low density permitted dynamic monitoring of cell proliferation. Selected colonies can be harvested from the surfaces by means of local trypsination. Thus, these techniques may provide useful tools for the isolation of clonal cell populations. Additionally, we demonstrate the possibility of surface-mediated gene delivery from the micro patterns. We show that DNA, complexed with a lipid reagent, can be adsorbed on modified poly(vinyl alcohol) coatings, resulting in spatially controlled adhesion and reverse transfection of HEK 293 cells.     

A versatile method for grafting polymers on nanoparticles

We report a simple and versatile method for grafting polymers on nanoparticles. A procedure was developed for the synthesis and subsequent functionalization of silica nanoparticles with a perfluorophenylazide. Polymers were then grafted by the photochemically induced insertion reactions of the perfluorophenylnitrene. Polystyrene, poly(4-vinylpyridine), and poly(2-ethyl-2-oxazoline) were successfully grafted on silica nanoparticles. Grafting density was studied with regard to polymer concentration and molecular weight.     

A new and versatile method for iodofunctionalization of 1,3-dienes

We wish to report the reactions of conjugated dienes with I(py)₂BF₄. This simple and general method allows the regiospecific 1,2-addition of iodine and a nucleophile to terminal dienes and the 1,4-addition to internal dienes.     

A versatile and general one-pot method for synthesizing bis-spiroketal motifs

[reaction: see text] A versatile and general method for the biomimetic construction of [5,5,5]- and [6,5,6]-bis-spiroketals, starting from easily accessible furan nuclei, by means of a powerful one-pot singlet oxygen-mediated cascade sequence is reported.     

A versatile method for the preparation of allenic alcohols

A convenient three step procedure to a variety of allenic alcohols is described, which relies on a highly unusual partitioning between two reaction pathways depending on the mode of addition of a reagent.     

A versatile method for the synthesis of 1,3-metallatitanacyclobutanes

The reaction of Cp₂TiCl₂ with two moles of CH₂(MgBr)₂ gave Cp₂Ti(CH₂MgBr)₂ which with Me₂MCl₂ (M  Si,Ge,Sn) was converted to the corresponding 1,3-metallatitanacyclobutanes.     

Ns strategies: a highly versatile synthetic method for amines

A highly efficient and versatile synthetic method for amines was established using nitrobenzenesulfonamides (Ns-amides) as both a protecting and activating group. The alkylation of N-monosubstituted Ns-amides either proceeded conventionally or under Mitsunobu conditions to provide the N,N-disubstituted sulfonamides, and the Ns group was removed easily with soft nucleophiles via Meisenheimer complexes to give the corresponding secondary amines. The major advantage of this protocol is that both alkylation and deprotection proceed under mild conditions. Thus, with this methodology, the total synthesis of linear and/or macrocyclic natural polyamines can be accomplished efficiently.     

Fluorous click chemistry as a practical tagging method

Highly efficient fluorous tagging methodology was developed based on catalytic 1,3-dipolar cycloaddition as the key step.     

A novel and versatile method for the enantioselective syntheses of tropane alkaloids

A full account of the novel and flexible approach to hydroxylated 8-azabicyclo[3,2,1]octan-3-ones and 9-azabicyclo[3,3,1]nonan-3-ones is presented.Using keto-lactams as the starting materials,this two-step method consists of silyl enol ether formation with TBDMSOTf,lactam activation with Tf2O/DTBMP,and halide-promoted cyclization.Radical dechlorination of the resulting 1-halotropan-3-ones led to the corresponding hydroxylated tropan-3-ones,which can be hydrogenated to yield3,6-dihydroxytropanes.Starting from optically active keto-lactams,the method has been applied to the enantioselective syntheses of(+)-(1S,3S,5R,6S)-pervilleine C(6),(+)-(1S,3R,5S,6R)-valeroidine(3),(+)-(1S,3S,5R,6S)-dibenzoyloxytropane(8),and(+)-(1S,3S,5R,6S)-merredissine(9).     

Laser vaporization: A versatile method for studying metal clusters

Vaporizing solid samples of metals and semiconductors with a YAG Laser is a method well suited for producing molecules and clusters of those materials. The clusters are examined by either laser-induced fluorescence (LIF) or mass spectroscopic methods. The technique is valuable for both gas phase and matrix studies. The method is described and some applications, studying either the structure of small metal molecules or their reactions, are reviewed, with emphasis on our recent results from the LIF studies of LiBe, Al₂ and the reaction of Al with oxygen, yielding A1₂O. For larger clusters, Ion Cyclotron Resonance is an extremely valuable method, as we demonstrate by its application to the reactions of small charged silicon clusters with strong oxidising agents.     

Precipitation as a simple and versatile method for preparation of optical nanochemosensors

Optical nanosensors for such important analytes as oxygen, pH, temperature, etc. are manufactured in a simple way via precipitation. Lipophilic indicators are entrapped into nanobeads based on poly(methyl methacrylate), polystyrene, polyurethanes, ethylcellulose, and other polymers. Charged groups greatly facilitate formation of the small beads and increase their stability. Sensing properties of the beads can be tuned by choosing the appropriate indicator. Nanosensors for carbon dioxide and ammonia are found to be cross-sensitive to pH if dispersed in aqueous media. These nanobeads are successfully employed to design bulk optodes. Nanochemosensors with enhanced brightness via light-harvesting and multi-functional magnetic nanosensors also are prepared.     

A versatile method for cyclic polymers from conjugated and unconjugated vinyl monomers

A versatile method was introduced to prepare cyclic polymers from both conjugated and unconjugated vinyl monomers. It was developed on the combination of the RAFT polymerization and the self‐accelerating double strain‐promoted azide‐alkyne click (DSPAAC) reaction. In this approach, a switchable chain transfer agent 1 was designed to have hydroxyl terminals and a functional pyridinyl group. The protonation and deprotonation of pyridinyl group endowed the chain transfer agent 1 with a switchable control capability to RAFT polymerization of both conjugated and unconjugated vinyl monomers. Based on this, RAFT polymerization and the following hydroxyl end group modification were used to prepare various azide‐terminated linear polymers including polystyrene, poly(N‐vinylcarbazole), and polystyrene‐block‐poly(N‐vinylcarbazole). Using sym‐dibenzo‐1,5‐cyclooctadiene‐3,7‐diyne (DBA) as small linkers, the corresponding cyclic polymers were then prepared via the DSPAAC reaction between DBA and azide terminals of the linear precursors. Due to the self‐accelerating property of DSPAAC reaction, this bimolecular ring‐closing reaction could efficiently produce the pure cyclic polymers using excess molar amounts of DBA to linear polymer precursors. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 1811–1820     

Simple gas chromatographic method for furfural analysis

A new, simple, gas chromatographic method was developed for the direct analysis of 5-hydroxymethylfurfural (5-HMF), 2-furfural (2-F) and 5-methylfurfural (5-MF) in liquid and water soluble foods, using direct immersion SPME coupled to GC-FID and/or GC-TOF-MS. The fiber (DVB/CAR/PDMS) conditions were optimized: pH effect, temperature, adsorption and desorption times. The method is simple and accurate (RSD<8%), showed good recoveries (77-107%) and good limits of detection (GC-FID: 1.37 microgL(-1) for 2-F, 8.96 microgL(-1) for 5-MF, 6.52 microgL(-1) for 5-HMF; GC-TOF-MS: 0.3, 1.2 and 0.9 ngmL(-1) for 2-F, 5-MF and 5-HMF, respectively). It was applied to different commercial food matrices: honey, white, demerara, brown and yellow table sugars, and white and red balsamic vinegars. This one-step, sensitive and direct method for the analysis of furfurals will contribute to characterise and quantify their presence in the human diet.     

Simple method for true coincidence summing correction

For the correction of losses due to true coincidences summing and edge effect, a simple method which is based on the ratio of a reference single -ray energy to that of cascade energies at near and far geometry is developed. The correction factors for several radioactive sources with simple and complex decay schemes are experimentally determined for three types of germanium detectors. It is shown that coincidence summing can be a complex effect and depends on the individual detector, the counting geometry and on the decay scheme of the radionuclide concerned.