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Full-Text Articles in Organic Chemistry

Effect Of Structure On The Spin Switching And Magnetic Bistability Of Solid-State Aryl Dicyanomethyl Monoradicals And Diradicals, Joshua P. Peterson, Rui Zhang, Arthur H. Winter Aug 2019

Effect Of Structure On The Spin Switching And Magnetic Bistability Of Solid-State Aryl Dicyanomethyl Monoradicals And Diradicals, Joshua P. Peterson, Rui Zhang, Arthur H. Winter

Chemistry Publications

Stable organic radicals with switchable spin states have applications in medicine, biology, and material science. An emerging class of such spin-switchable radicals is based on dicyanomethyl radicals, which are typically thermally and air-stable species that form weakly bonded (closed-shell singlet) dimers at a lower temperature that rupture into electron paramagnetic resonance-active diradicals at a higher temperature. However, thus far, the study of these dicyanomethyl radicals has focused on their solution-phase behavior. An understanding of how chemical structure affects the solid-state spin switching behavior for these radicals is unknown. Here, we examine the solid-state spin crossover behavior of 6 monoradicals and ...


Toward Mass Spectrometry Imaging In The Metabolomics Scale: Increasing Metabolic Coverage Through Multiple On-Tissue Chemical Modifications, Maria Emilia Dueñas, Evan A. Larson, Young Jin Lee Jul 2019

Toward Mass Spectrometry Imaging In The Metabolomics Scale: Increasing Metabolic Coverage Through Multiple On-Tissue Chemical Modifications, Maria Emilia Dueñas, Evan A. Larson, Young Jin Lee

Chemistry Publications

Exploring the metabolic differences directly on tissues is essential for the comprehensive understanding of how multicellular organisms function. Mass spectrometry imaging (MSI) is an attractive technique toward this goal; however, MSI in metabolomics scale has been hindered by multiple limitations. This is most notable for single cell level high-spatial resolution imaging because of the limited number of molecules in small sampling size and the low ionization yields of many metabolites. Several on-tissue chemical derivatization approaches have been reported to increase MSI signals of targeted compounds, especially in matrix-assisted laser desorption/ionization (MALDI)- MSI. Herein, we adopt a combination of chemical ...


Organic Chemistry With A Biographical Emphasis: Solutions To In-Chapter Exercises, Timothy Soderberg Jul 2019

Organic Chemistry With A Biographical Emphasis: Solutions To In-Chapter Exercises, Timothy Soderberg

Chemistry Publications

The solutions to the in-chapter exercises of Organic Chemistry with a Biological Emphasis volume 1 and 2.


Organic Chemistry With A Biological Emphasis: Solutions To Selected End-Of-Chapter Problems, Timothy Soderberg Jul 2019

Organic Chemistry With A Biological Emphasis: Solutions To Selected End-Of-Chapter Problems, Timothy Soderberg

Chemistry Publications

The solutions to the in-chapter exercises of Organic Chemistry with a Biological Emphasis volume 1 and 2.


Organic Chemistry With A Biological Emphasis Volume I, Timothy Soderberg Jul 2019

Organic Chemistry With A Biological Emphasis Volume I, Timothy Soderberg

Chemistry Publications

The traditional approach to teaching Organic Chemistry, taken by most of the textbooks that are currently available, is to focus primarily on the reactions of laboratory synthesis, with much less discussion - in the central chapters, at least - of biological molecules and reactions. This is despite the fact that, in many classrooms, a majority of students are majoring in Biology or Health Sciences rather than in Chemistry, and are presumably taking the course in order to learn about the chemistry that takes place in living things.

In an effort to address this disconnect, I have developed a textbook for a two-semester ...


Organic Chemistry With A Biological Emphasis Volume Ii, Timothy Soderberg Jul 2019

Organic Chemistry With A Biological Emphasis Volume Ii, Timothy Soderberg

Chemistry Publications

The traditional approach to teaching Organic Chemistry, taken by most of the textbooks that are currently available, is to focus primarily on the reactions of laboratory synthesis, with much less discussion - in the central chapters, at least - of biological molecules and reactions. This is despite the fact that, in many classrooms, a majority of students are majoring in Biology or Health Sciences rather than in Chemistry, and are presumably taking the course in order to learn about the chemistry that takes place in living things.

In an effort to address this disconnect, I have developed a textbook for a two-semester ...


Efficient, Scalable Syntheses Of Ginkgolic Acids, Joshua L. Alterman, George A. Kraus Jun 2019

Efficient, Scalable Syntheses Of Ginkgolic Acids, Joshua L. Alterman, George A. Kraus

Chemistry Publications

Ginkgolic acids were directly synthesized from 6-methylsalicylic acid using a sequence involving protection of the phenol and acid as methoxymethyl ethers and esters, lateral alkylation and deprotection under mild aqueous acid conditions.


Spatial Distribution Of Organic Functional Groups Supported On Mesoporous Silica Nanoparticles (2): A Study By 1h Triple-Quantum Fast-Mas Solid-State Nmr, Takeshi Kobayashi, Dilini Singappuli-Arachchige, Igor I. Slowing, Marek Pruski Aug 2018

Spatial Distribution Of Organic Functional Groups Supported On Mesoporous Silica Nanoparticles (2): A Study By 1h Triple-Quantum Fast-Mas Solid-State Nmr, Takeshi Kobayashi, Dilini Singappuli-Arachchige, Igor I. Slowing, Marek Pruski

Chemistry Publications

The distribution of organic functional groups attached to the surface of mesoporous silica nanoparticles (MSNs) via co-condensation was scrutinized using 1D and 2D 1H solid-state NMR, including the triple-quantum/single-quantum (TQ/SQ) homonuclear correlation technique. The excellent sensitivity of 1H NMR and high resolution provided by fast magic angle spinning (MAS) allowed us to study surfaces with very low concentrations of aminopropyl functional groups. The sequential process, in which the injection of tetraethyl orthosilicate (TEOS) into the aqueous mother liquor was followed by dropwise addition of the organosilane precursor, resulted in deployment of organic groups on the surface, which were ...


Open Resonance Assisted Hydrogen Bonds And Competing Quasiaromaticity, Yen H. Nguyen, Bryan J. Lampkin, Amrit Venkatesh, Arkady Ellern, Aaron J. Rossini, Brett Vanveller Jul 2018

Open Resonance Assisted Hydrogen Bonds And Competing Quasiaromaticity, Yen H. Nguyen, Bryan J. Lampkin, Amrit Venkatesh, Arkady Ellern, Aaron J. Rossini, Brett Vanveller

Chemistry Publications

The delocalization of electron density upon tautomerization of a proton across a conjugated bridge can alter the strength of hydrogen bonds. This effect has been dubbed resonance-assisted hydrogen bonding (RAHB) and plays a major role in the energetics of the tautomeric equilibrium. The goal of this work was to investigate the role that π-delocalization plays in the stability of RAHBs by engaging other isomerization processes. Similarly, acid-base chemistry has received little experimental attention in studies of RAHB and we address the role that acid-base effects play in the tautomeric equilibrium. We find that π-delocalization and the disruption of adjacent aromatic ...


Indole Anion Cycloadditions With Methyl Coumalate, George A. Kraus, Huangchao Yu Feb 2018

Indole Anion Cycloadditions With Methyl Coumalate, George A. Kraus, Huangchao Yu

Chemistry Publications

The reaction of the anion of indoles with methyl coumalate followed by selective opening of the lactone led to the preparation of tricyclic intermediates for indole alkaloid synthesis.


The Oligomerization State Of Bacterial Enzyme I (Ei) Determines Ei's Allosteric Stimulation Or Competitive Inhibition By Α-Ketoglutarate, Trang T. Nguyen, Rodolfo Ghirlando, Vincenzo Venditti Feb 2018

The Oligomerization State Of Bacterial Enzyme I (Ei) Determines Ei's Allosteric Stimulation Or Competitive Inhibition By Α-Ketoglutarate, Trang T. Nguyen, Rodolfo Ghirlando, Vincenzo Venditti

Chemistry Publications

The bacterial phosphotransferase system (PTS) is a signal transduction pathway that couples phosphoryl transfer to active sugar transport across the cell membrane. The PTS is initiated by phosphorylation of enzyme I (EI) by phosphoenolpyruvate (PEP). The EI phosphorylation state determines the phosphorylation states of all other PTS components and is thought to play a central role in the regulation of several metabolic pathways and to control the biology of bacterial cells at multiple levels, for example, affecting virulence and biofilm formation. Given the pivotal role of EI in bacterial metabolism, an improved understanding of the mechanisms controlling its activity could ...


Synthesis Of Isophthalates From Methyl Coumalate, George A. Kraus, Shuai Wang Dec 2017

Synthesis Of Isophthalates From Methyl Coumalate, George A. Kraus, Shuai Wang

Chemistry Publications

Methyl coumalate reacts with enol ethers to form stable adducts which can be converted into isophthalates in good to excellent yields. Alkyl vinyl ethers afford higher yields of isophthalates than enol silyl ethers. The adduct of the enol silyl ether of acetophenone with methyl coumalate reacted with PTSA to produce a styryl coumalate.


Rapid Assembly Of The Procyanidin A Skeleton, George A. Kraus, Ivan M. Geraskin Dec 2017

Rapid Assembly Of The Procyanidin A Skeleton, George A. Kraus, Ivan M. Geraskin

Chemistry Publications

Arylpropynals and two equivalents of phloroglucinol react to produce pentacyclic ketals. In addition, 4-methoxydibromocinnamaldehyde also reacted to form procyanidin A-skeleton.


Homoleptic Trivalent Tris(Alkyl) Rare Earth Compounds, Aradhana Pindwal, Kaking Yan, Smita Patnaik, Bradley M. Schmidt, Arkady Ellern, Igor I. Slowing, Cheolbeom Bae, Aaron D. Sadow Oct 2017

Homoleptic Trivalent Tris(Alkyl) Rare Earth Compounds, Aradhana Pindwal, Kaking Yan, Smita Patnaik, Bradley M. Schmidt, Arkady Ellern, Igor I. Slowing, Cheolbeom Bae, Aaron D. Sadow

Chemistry Publications

Homoleptic tris(alkyl) rare earth complexes Ln{C(SiHMe2)(3)}(3) (Ln = La, 1a; Ce, 1b; Pr, 1c; Nd, 1d) are synthesized in high yield from LnI(3)THF(n) and 3 equiv of KC(SiHMe2)(3). X-ray diffraction studies reveal 1a-d are isostructural, pseudo-C-3-symmetric molecules that contain two secondary Li <- HSi interactions per alkyl ligand (six total). Spectroscopic assignments are supported by comparison with Ln{C(SiDMe2)(3)}(3) and DFT calculations. The Ln <- HSi and terminal SiH exchange rapidly on the NMR time scale at room temperature, but the two motifs are resolved at low temperature. Variable-temperature NMR studies provide activation parameters for the exchange process in la (Delta H-double dagger = 8.2(4) kcal.mol(-1); Delta S-double dagger = -1(2) cal.mol(-1)K(-1)) and 1a-d(9) (Delta H-double dagger = 7.7(3) kcal.mol(-1); Delta S-double dagger = -4(2) cal.mol(-1)K(-1)). Comparisons of lineshapes, rate constants, (k(H)/k(D)), and slopes of ln (k/T) vs 1/T plots for la and 1a-d(9) reveal that an inverse isotope effect dominates at low temperature. DFT calculations identify four low-energy intermediates containing five beta-Si-H -> Ln and one gamma-C-H -> Ln. The calculations also suggest the pathway for Ln <- HSi/SiH exchange involves rotation of a single C(SiHMe2)(3) ligand that is coordinated to the Ln center through the Ln-C bond and one secondary interaction. These robust organometallic compounds persist in solution and in the solid state up to 80 degrees C, providing potential for their use in a range of synthetic applications. For example, reactions of Ln{C(SiHMe2)(3)}(3) and ancillary proligands, such as bis-1,1-(4,4-dimethyl-2-oxazolinyl)ethane (HMeC(Ox(Me2))(2)) give {MeC(Ox(Me2))(2)}Ln{C(SiHMe2)(3)}(2), and reactions with disilazanes provide solvent-free lanthanoid tris(disilazides).


Spatial Mapping And Profiling Of Metabolite Distributions During Germination, Adam D. Feenstra, Liza E. Alexander, Zhihong Song, Andrew R. Korte, Marna D. Yandeau-Nelson, Basil J. Nikolau, Young-Jin Lee Aug 2017

Spatial Mapping And Profiling Of Metabolite Distributions During Germination, Adam D. Feenstra, Liza E. Alexander, Zhihong Song, Andrew R. Korte, Marna D. Yandeau-Nelson, Basil J. Nikolau, Young-Jin Lee

Chemistry Publications

Germination is a highly complex process by which seeds begin to develop and establish themselves as viable organisms. In this paper, we utilize a combination of GC-MS, LC-fluorescence, and mass spectrometry imaging (MSI) approaches to profile and visualize the metabolic distributions of germinating seeds from two different inbreds of maize seeds, B73 and Mo17. GC and LC analyses demonstrate that the two inbreds are highly differentiated in their metabolite profiles throughout the course of germination, especially with regard to amino acids, sugar alcohols, and small organic acids. Crude dissection of the seed followed by GC-MS analysis of polar metabolites also ...


Anomalous Effect Of Non-Alternant Hydrocarbons On Carbocation And Carbanion Electronic Configurations, Logan J. Fischer, Andrew S. Dutton, Arthur H. Winter Jun 2017

Anomalous Effect Of Non-Alternant Hydrocarbons On Carbocation And Carbanion Electronic Configurations, Logan J. Fischer, Andrew S. Dutton, Arthur H. Winter

Chemistry Publications

Carbocations are widely viewed to be closed-shell singlet electrophiles. Here, computations show that azulenyl-substituted carbocations have triplet ground states. This triplet ground state for azulenyl carbocations stands in striking contrast to the isomeric naphthenyl carbocation, which is a normal closed-shell singlet with a large singlet–triplet gap. Furthermore, substitution of the azulenyl carbocation can substantially alter the energy gap between the different electronic configurations and can manipulate the ground state towards either the singlet or the triplet state depending on the nature and location of the substituent. A detailed investigation into the origin of this spin state reversal, including NICS ...


Β-Sih-Containing Tris(Silazido) Rare-Earth Complexes As Homogeneous And Grafted Single-Site Catalyst Precursors For Hydroamination, Naresh Eedugurala, Zhuoran Wang, Kaking Yan, Kasuni Boteju, Umesh Chaudhary, Takeshi Kobayashi, Arkady Ellern, Igor I. Slowing, Marek Pruski, Aaron D. Sadow Jan 2017

Β-Sih-Containing Tris(Silazido) Rare-Earth Complexes As Homogeneous And Grafted Single-Site Catalyst Precursors For Hydroamination, Naresh Eedugurala, Zhuoran Wang, Kaking Yan, Kasuni Boteju, Umesh Chaudhary, Takeshi Kobayashi, Arkady Ellern, Igor I. Slowing, Marek Pruski, Aaron D. Sadow

Chemistry Publications

A series of homoleptic rare-earth silazido compounds and their silica-grafted derivatives were prepared to compare spectroscopic and catalytic features under homogeneous and interfacial conditions. Trivalent tris(silazido) compounds Ln{N(SiHMe2)tBu}3 (Ln = Sc (1), Y (2), Lu (3)) are prepared in high yield by salt metathesis reactions. Solution-phase and solid-state characterization of 13 by NMR and IR spectroscopy and X-ray diffraction reveals Ln↼H–Si interactions. These features are retained in solvent-coordinated 2·Et2O, 2·THF, and 3·THF. The change in spectroscopic features characterizing the secondary interactions (νSiH, 1JSiH) from the ...


A General Method For Selective Recognition Of Monosaccharides And Oligosaccharides In Water, Roshan W. Gunasekara, Yan Zhao Jan 2017

A General Method For Selective Recognition Of Monosaccharides And Oligosaccharides In Water, Roshan W. Gunasekara, Yan Zhao

Chemistry Publications

Molecular recognition of carbohydrates plays vital roles in biology but has been difficult to achieve with synthetic receptors. Through covalent imprinting of carbohydrates in boroxole-functionalized cross-linked micelles, we prepared nanoparticle receptors for a wide variety of mono- and oligosaccharides. The boroxole functional monomer bound the sugar templates through cis-1,2-diol, cis-3,4-diol, and trans-4,6-diol. The protein-sized nanoparticles showed excellent selectivity for d-aldohexoses in water with submillimolar binding affinities and completely distinguished the three biologically important hexoses (glucose, mannose, and galactose). Glycosides with nonpolar aglycon showed stronger binding due to enhanced hydrophobic interactions. Oligosaccharides were distinguished on ...


Imprinted Micelles For Chiral Recognition In Water: Shape, Depth, And Number Of Recognition Sites, Joseph K. Awino, Yan Zhao Jan 2017

Imprinted Micelles For Chiral Recognition In Water: Shape, Depth, And Number Of Recognition Sites, Joseph K. Awino, Yan Zhao

Chemistry Publications

Chiral molecular recognition is important to biology, separation, and asymmetric catalysis. Because there is no direct correlation between the chiralities of the host and the guest, it is difficult to design a molecular receptor for a chiral guest in a rational manner. By cross-linking surfactant micelles containing chiral template molecules, we obtained chiral nanoparticle receptors for a number of 4-hydroxyproline derivatives. Molecular imprinting allowed us to transfer the chiral information directly from the guest to host, making the molecular recognition between the two highly predictable. Hydrophobic interactions between the host and the guest contributed strongly to the enantio- and diastereoselective ...


Sequence-Selective Binding Of Oligopeptides In Water Through Hydrophobic Coding, Joseph K. Awino, Roshan W. Gunasekara, Yan Zhao Jan 2017

Sequence-Selective Binding Of Oligopeptides In Water Through Hydrophobic Coding, Joseph K. Awino, Roshan W. Gunasekara, Yan Zhao

Chemistry Publications

A general method for sequence-specific binding of peptides remains elusive despite decades of research. By creating an array of “hydrophobically coded dimples” on the surface of surface–core doubly cross-linked micelles, we synthesized water-soluble nanoparticle receptors to recognize peptides by the location, number, and nature of their hydrophobic side chains. Minute differences in the side chains could be distinguished, and affinities up to 20 nM were obtained for biologically active oligopeptides in water.


A Direct Synthesis Of Atractylodinol, A Potent Inhibitor Of Prrsv, And Its Biological Evaluation, George A. Kraus, Pengfei Dong, Yang Qu, Alyssa Evans, Susan Carpenter Nov 2016

A Direct Synthesis Of Atractylodinol, A Potent Inhibitor Of Prrsv, And Its Biological Evaluation, George A. Kraus, Pengfei Dong, Yang Qu, Alyssa Evans, Susan Carpenter

Chemistry Publications

A direct synthesis of atractylodinol from 2-furylbutenyne and bromoacetylene 6 is reported. Both compounds 1 and 8 showed greater than 99% virus inhibition.


Synthesis, Self-Assembly, And Immunological Activity Of Α-Galactose-Functionalized Dendron–Lipid Amphiphiles, John Trant, Namrata Jain, D. M. Mazzuca, J Trevor Mcintosh, Bo Fan, S M Mansour Haeryfar, Sebastien Lecommandoux, Elizabeth Gillies Sep 2016

Synthesis, Self-Assembly, And Immunological Activity Of Α-Galactose-Functionalized Dendron–Lipid Amphiphiles, John Trant, Namrata Jain, D. M. Mazzuca, J Trevor Mcintosh, Bo Fan, S M Mansour Haeryfar, Sebastien Lecommandoux, Elizabeth Gillies

Chemistry Publications

Nanoassemblies presenting multivalent displays of biologically active carbohydrates are of significant interest for a wide array of biomedical applications ranging from drug delivery to immunotherapy. In this study, glycodendronlipid hybrids were developed as a new and tunable class of dendritic amphiphiles. A modular synthesis was used to prepare dendronlipid hybrids comprising distearylglycerol and 0 through 4th generation polyester dendrons with peripheral protected amines. Following deprotection of the amines, an isothiocyanate derivative of C-linked α-galactose (α-Gal) was conjugated to the dendron peripheries, affording amphiphiles with 1 to 16 α-Gal moieties. Self-assembly in water through a ...


Characterizing Electric Field Exposed P3ht Thin Films Using Polarized‐Light Spectroscopies, Ujjal Bhattacharjee, Moneim Elshobaki, Kalyan Santra, Jonathan M. Bobbitt, Sumit Chaudhary, Emily A. Smith, Jacob W. Petrich Aug 2016

Characterizing Electric Field Exposed P3ht Thin Films Using Polarized‐Light Spectroscopies, Ujjal Bhattacharjee, Moneim Elshobaki, Kalyan Santra, Jonathan M. Bobbitt, Sumit Chaudhary, Emily A. Smith, Jacob W. Petrich

Chemistry Publications

P3HT (poly (3‐hexylthiophene)) has been widely used as a donor in the active layer in organic photovoltaic devices. Although moderately high‐power conversion efficiencies have been achieved with P3HT‐based devices, structural details, such as the orientation of polymer units and the extent of H‐ and J‐aggregation are not yet fully understood; and different measures have been taken to control the ordering in the material. One such measure, which has been exploited, is to apply an electric field from a Van de Graaff generator. Fluorescence (to measure anisotropy instead of polarization, which is more commonly measured) and Raman ...


Surface-Cross-Linked Micelles As Multifunctionalized Organic Nanoparticles For Controlled Release, Light Harvesting, And Catalysis, Yan Zhao May 2016

Surface-Cross-Linked Micelles As Multifunctionalized Organic Nanoparticles For Controlled Release, Light Harvesting, And Catalysis, Yan Zhao

Chemistry Publications

Surfactant micelles are dynamic entities with a rapid exchange of monomers. By “clicking” tripropargylammonium-containing surfactants with diazide cross-linkers, we obtained surface-cross-linked micelles (SCMs) that could be multifunctionalized for different applications. They triggered membrane fusion through tunable electrostatic interactions with lipid bilayers. Antenna chromophores could be installed on them to create artificial light-harvesting complexes with efficient energy migration among tens to hundreds of chromophores. When cleavable cross-linkers were used, the SCMs could break apart in response to redox or pH signals, ejecting entrapped contents quickly as a result of built-in electrostatic stress. They served as caged surfactants whose surface activity was ...


Derivation And Implementation Of The Gradient Of The R–7 Dispersion Interaction In The Effective Fragment Potential Method, Emilie B. Guidez, Peng Xu, Mark S. Gordon Jan 2016

Derivation And Implementation Of The Gradient Of The R–7 Dispersion Interaction In The Effective Fragment Potential Method, Emilie B. Guidez, Peng Xu, Mark S. Gordon

Chemistry Publications

The dispersion interaction energy may be expressed as a sum over Rn terms, with n ≥ 6. Most implementations of the dispersion interaction in model potentials are terminated at n = 6. Those implementations that do include higher order contributions commonly only include even power terms, despite the fact that odd power terms can be important. Because the effective fragment potential (EFP) method contains no empirically fitted parameters, the EFP method provides a useful vehicle for examining the importance of the leading R–7 odd power term in the dispersion expansion. To fully evaluate the importance of the R–7 contribution ...


Selective Recognition Of D-Aldohexoses In Water By Boronic Acid-Functionalized Molecularly Imprinted Cross-Linked Micelles, Joseph K. Awino, Roshan W. Gunasekara, Yan Zhao Jan 2016

Selective Recognition Of D-Aldohexoses In Water By Boronic Acid-Functionalized Molecularly Imprinted Cross-Linked Micelles, Joseph K. Awino, Roshan W. Gunasekara, Yan Zhao

Chemistry Publications

Molecular imprinting within cross-linked micelles using 4-vinylphenylboronate derivatives of carbohydrates provided water-soluble nanoparticle receptors selective for the carbohydrate templates. Complete differentiation of d-aldohexoses could be achieved by these receptors if a single inversion of hydroxyl occurred at C2 or C4 of the sugar or if two or more inversions took place. Glycosides with a hydrophobic aglycan displayed stronger binding due to increased hydrophobic interactions.


Recent Advances In Transition Metal-Catalysed Hydroacylation Of Alkenes And Alkynes, Avipsa Ghosh, Kirsten F. Johnson, Kevin L. Vickerman, James A. Walker Jr., Levi M. Stanley Jan 2016

Recent Advances In Transition Metal-Catalysed Hydroacylation Of Alkenes And Alkynes, Avipsa Ghosh, Kirsten F. Johnson, Kevin L. Vickerman, James A. Walker Jr., Levi M. Stanley

Chemistry Publications

This highlight discusses developments in transition metal-catalysed alkene and alkyne hydroacylation reactions over the past three years. The discussion summarizes the development of new catalyst systems for alkene and alkyne hydroacylation and applications to the synthesis of important ketone building blocks. The highlight captures transition metal-catalysed alkene and alkyne hydroacylation at a time of impressive growth when cobalt, nickel, ruthenium, and iridium catalysts are emerging as complements or replacements for traditional rhodium catalysts.


Homoleptic Divalent Dialkyl Lanthanide-Catalyzed Cross-Dehydrocoupling Of Silanes And Amines, Aradhana Pindwal, Arkady Ellern, Aaron D. Sadow Jan 2016

Homoleptic Divalent Dialkyl Lanthanide-Catalyzed Cross-Dehydrocoupling Of Silanes And Amines, Aradhana Pindwal, Arkady Ellern, Aaron D. Sadow

Chemistry Publications

The rare-earth bis(alkyl) compound Sm{C(SiHMe2)3}2THF2 (1b) is prepared by the reaction of samarium(II) iodide and 2 equiv of KC(SiHMe2)3. This synthesis is similar to that of previously reported Yb{C(SiHMe2)3}2THF2 (1a), and compounds 1a,b are isostructural. Reactions of 1b and 1 or 2 equiv of B(C6F5)3 afford SmC(SiHMe2)3HB(C6F5)3THF2 (2b) or Sm{HB(C6F5)3}2THF2 (3b), respectively, and 1,3-disilacyclobutane {Me2Si-C(SiHMe2)2}2 as a byproduct. Bands from 2300 to 2400 cm–1 assigned to νBH in the IR spectra and ...


Controlling Catalytic Properties Of Pd Nanoclusters Through Their Chemical Environment At The Atomic Level Using Isoreticular Metal–Organic Frameworks, Xinle Li, Tian Wei Goh, Lei Li, Zhiyong Guo, Xiao Cheng Zeng, Wenyu Huang Jan 2016

Controlling Catalytic Properties Of Pd Nanoclusters Through Their Chemical Environment At The Atomic Level Using Isoreticular Metal–Organic Frameworks, Xinle Li, Tian Wei Goh, Lei Li, Zhiyong Guo, Xiao Cheng Zeng, Wenyu Huang

Chemistry Publications

Control of heterogeneous catalytic sites through their surrounding chemical environment at an atomic level is crucial to catalyst design. We synthesize Pd nanoclusters (NCs) in an atomically tunable chemical environment using isoreticular metal–organic framework (MOF) supports (Pd@UiO-66-X, X = H, NH2, OMe). In an aerobic reaction between benzaldehyde and ethylene glycol, these catalysts show product distributions that are completely altered from the acetal to the ester when we change the functional groups on the MOF linkers from −NH2 to −H/–OMe. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) studies, along with density functional theory (DFT) calculations, show ...


Enantioselective Dearomative [3 + 2] Cycloadditions Of Indoles With Azomethine Ylides Derived From Alanine Imino Esters, Anthony L. Gerten, Levi M. Stanley Jan 2016

Enantioselective Dearomative [3 + 2] Cycloadditions Of Indoles With Azomethine Ylides Derived From Alanine Imino Esters, Anthony L. Gerten, Levi M. Stanley

Chemistry Publications

Catalytic, enantioselective [3 + 2] cycloadditions of azomethine ylides derived from alanine imino esters with 3-nitroindoles are reported. The dearomative cycloaddition reactions occur in the presence of a catalyst generated in situfrom Cu(OTf)2 and (R)-Difluorphos to form exo′-pyrroloindoline cycloadducts and establish four contiguous stereogenic centers, two of which are fully substituted. The exo′-pyrroloindoline products are formed in moderate-to-good yields (39–85%) with high diastereoselectivities (up to 98:1:1 dr) and enantioselectivities (up to 96% ee).