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Chemistry Publications

Chemistry

2011

Articles 1 - 9 of 9

Full-Text Articles in Physical Sciences and Mathematics

The Formal [4+3] Cycloaddition Between Donor-Acceptor Cyclobutanes And Nitrones., Andrew C Stevens, Cory Palmer, Brian L Pagenkopf Mar 2011

The Formal [4+3] Cycloaddition Between Donor-Acceptor Cyclobutanes And Nitrones., Andrew C Stevens, Cory Palmer, Brian L Pagenkopf

Chemistry Publications

The formal [4+3] cycloaddition of 2-alkoxy-1,1-dicarboxylate activated donor-acceptor cyclobutanes with nitrones is disclosed. The reaction forms structurally unique oxazepines in moderate to high yield with a wide scope of nitrones. In most cases either a diastereomeric mixture or a single diastereomer may be formed, depending on the reaction conditions.

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The Formal [4+3] Cycloaddition Between Donor-Acceptor Cyclobutanes And Nitrones., Andrew C Stevens, Cory Palmer, Brian L Pagenkopf Feb 2011

The Formal [4+3] Cycloaddition Between Donor-Acceptor Cyclobutanes And Nitrones., Andrew C Stevens, Cory Palmer, Brian L Pagenkopf

Chemistry Publications

The formal [4+3] cycloaddition of 2-alkoxy-1,1-dicarboxylate activated donor-acceptor cyclobutanes with nitrones is disclosed. The reaction forms structurally unique oxazepines in moderate to high yield with a wide scope of nitrones. In most cases either a diastereomeric mixture or a single diastereomer may be formed, depending on the reaction conditions.

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Gram Scale Synthesis Of The C(18)-C(34) Fragment Of Amphidinolide C., Nicholas A Morra, Brian L Pagenkopf Feb 2011

Gram Scale Synthesis Of The C(18)-C(34) Fragment Of Amphidinolide C., Nicholas A Morra, Brian L Pagenkopf

Chemistry Publications

The synthesis of the C(18)-C(34) fragment of amphidinolide C has been achieved via two routes, culminating in both the shortest (11 steps) and highest yielding (26% overall yield) approaches to this segment. The highly convergent approach will facilitate the synthesis of analogues, including the C(18)-C(29) fragment of amphidinolide F. Synthetic highlights include the selective methylation of a diyne, and the highly efficient use of a second generation cobalt catalyst in the Mukaiyama oxidative cyclization to form the trans-THF ring.

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Gram Scale Synthesis Of The C(18)-C(34) Fragment Of Amphidinolide C., Nicholas A Morra, Brian L Pagenkopf Jan 2011

Gram Scale Synthesis Of The C(18)-C(34) Fragment Of Amphidinolide C., Nicholas A Morra, Brian L Pagenkopf

Chemistry Publications

The synthesis of the C(18)-C(34) fragment of amphidinolide C has been achieved via two routes, culminating in both the shortest (11 steps) and highest yielding (26% overall yield) approaches to this segment. The highly convergent approach will facilitate the synthesis of analogues, including the C(18)-C(29) fragment of amphidinolide F. Synthetic highlights include the selective methylation of a diyne, and the highly efficient use of a second generation cobalt catalyst in the Mukaiyama oxidative cyclization to form the trans-THF ring.

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Characterization Of Oxidation Resistant Fe@M (M=Cr, Ni) Core@Shell Nanoparticles Prepared By A Modified Reverse Micelle Reaction, Sweta H. Naik, Kyler J. Carroll, Everett E. Carpenter Jan 2011

Characterization Of Oxidation Resistant Fe@M (M=Cr, Ni) Core@Shell Nanoparticles Prepared By A Modified Reverse Micelle Reaction, Sweta H. Naik, Kyler J. Carroll, Everett E. Carpenter

Chemistry Publications

Iron-based nanoparticles are the forerunners in the field of nanotechnology due to their high magnetizationsaturation and biocompability which affords them use in a variety of applications. However, iron-based nanoparticles, due to a high surface-to-volume ratio, suffer from oxidation and limit its practicality by lowering the magnetic moment significantly. To avoid this oxidation, the surfaces of the particles have to be passivated. One such way to accomplish this passivation is to synthesize core@shell nanoparticles that have a surface treatment of chromium or nickel. These core@shell nanoparticles have been synthesized using a reverse micelle technique. The Cr and Ni passivated ironnanoparticles were …

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Synthesis Of High Magnetization Feco Alloys Prepared By A Modified Polyol Process, Zachary J. Huba, Kyler J. Carroll, Everett E. Carpenter Jan 2011

Synthesis Of High Magnetization Feco Alloys Prepared By A Modified Polyol Process, Zachary J. Huba, Kyler J. Carroll, Everett E. Carpenter

Chemistry Publications

High magnetization, soft ferromagnetic FeCo alloy nanoparticles were synthesized at various Fe to Co ratios using a modified polyol process. Transmission electron microscopy images revealed that Fe-rich particles had a cubic shape with a mean particle size of 100 nm, while Co-rich particles had a spherical shape. A maximum saturation magnetization of 212 emu/g was recorded for both Fe60Co40 and Fe75Co25 particles. X-ray diffraction scans at room temperatureof synthesized particles were characteristic of body-centered-cubic single-phase FeCo. Variabletemperature x-ray diffraction scans under N2 gas revealed an order–disorder transition at 600 °C and a transition …

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Spin Transition In Gd3n@C-80, Detected By Low-Temperature On-Chip Squid Technique, L. Chen, E. E. Carpenter, C. S. Hellberg, H. C. Dorn, M. Schultz, W/ Wernsdorfer, I. Chiorescu Jan 2011

Spin Transition In Gd3n@C-80, Detected By Low-Temperature On-Chip Squid Technique, L. Chen, E. E. Carpenter, C. S. Hellberg, H. C. Dorn, M. Schultz, W/ Wernsdorfer, I. Chiorescu

Chemistry Publications

We present a magnetic study of the Gd3N@C80 molecule, consisting of a Gd-trimer via a nitrogen atom, encapsulated in a C80 cage. This molecular system can be an efficient contrast agent for magnetic resonance imaging (MRI) applications. We used a low-temperature technique able to detect small magnetic signals by placing the sample in the vicinity of an on-chip SQUID. The technique implemented at the National High Magnetic Field Laboratory has the particularity of being able to operate in high magnetic fields of up to 7 T. The Gd3N@C80shows a paramagnetic behavior and …

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Structure And Hydration Of The C4h4 •+ Ion Formed By Electron Impact Ionization Of Acetylene Clusters, Paul O. Momoh, Ahmed Hamid, Samuel A. Abrash, M. Samy El-Shall Jan 2011

Structure And Hydration Of The C4h4 •+ Ion Formed By Electron Impact Ionization Of Acetylene Clusters, Paul O. Momoh, Ahmed Hamid, Samuel A. Abrash, M. Samy El-Shall

Chemistry Publications

Here we report ion mobility experiments and theoretical studies aimed at elucidating the identity of the acetylene dimer cation and its hydrated structures. The mobility measurement indicates the presence of more than one isomer for the C4H4 •+ ion in the cluster beam. The measured average collision cross section of the C4H4 •+ isomers in helium (38.9 ± 1 Å2) is consistent with the calculated cross sections of the four most stable covalent structures calculated for the C4H4 •+ ion [methylenecyclopropene (39.9 Å2), 1,2,3-butatriene (41.1 Å2), cyclobutadiene (38.6 Å2), and vinyl acetylene …

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Bf3·Oet2 Catalyzed Reaction Of Donor-Acceptor Cyclobutanes With Terminal Alkynes: Single Step Access To 2,3-Dihydrooxepines, Ben P Machin, Brian L Pagenkopf Jan 2011

Bf3·Oet2 Catalyzed Reaction Of Donor-Acceptor Cyclobutanes With Terminal Alkynes: Single Step Access To 2,3-Dihydrooxepines, Ben P Machin, Brian L Pagenkopf

Chemistry Publications

In the presence of BF3˙OEt2 cyclobutane-1,1-diesters undergo a reaction with terminal alkynes to quickly access dihydro­oxepines.

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