Chemistry Commons^™

Reactions With Platinum (Ll) Complexes And Selenium-Containing Amino Acids, Stephanie Robey

Mahurin Honors College Capstone Experience/Thesis Projects

We have reacted [Pt(Me₄en)(D₂O)₂]²⁺ [Me₄En=N,N,N’N’-tetramethylethylenediamine] with Selenomethionine (SeMet), Methionine (Met), and Methylselenocysteine (MeSeCys). When MeSeCys was reacted with [Pt(Me₄en)(D₂O)₂]²⁺, we observed both stereoisomers of Se,N chelates, as well as [Pt(Me₄en)(MeSeCys)Cl]⁺ from ­¹­H NMR Spectroscopy; the latter formed due to the presence of Cl^- in the solution. Both isomers of the chelate seemed to form proportionally to one another, not favoring a specific stereoisomer. Eventually the [Pt(Me₄en)(MeSeCys)Cl]⁺ products became Se,N chelates. We incubated SeMet with …

Fabrication Of Mineralized Collagen From Bovine Waste Materials By Hydrothermal Method As Promised Biomaterials, Faheem A. Sheikh, M. A. Kanjwal, Javier Macossay-Torres, Muneeb A. Muhammad, Travis Cantu, Ioannis S. Chronakis, N. A. M. Barakat, Hak Yong Kim

Chemistry Faculty Publications and Presentations

In the present study, we aimed to produce mineralized-collagen by hydrothermal process. A simple method not depending on additional foreign chemicals has been employed to isolate the mineralized-collagen fibers from bovine waste. The process of extraction involves the use of hydrothermal method from available bovine bones. The structural and morphological properties of the collagen fibers were characterized by using scanning electron microscopy and transmission electron microscopy. These results indicated well received collagen fibers, having a diameter less than 1 μm and with established mineral content in the individual fibers. The X-ray diffraction showed the crystalline feature of the obtained nano-compounds. …

Exploring The Roles Of Nucleobase Desolvation And Shape Complementarity During The Misreplication Of O6-Methylguanine, Delia Chavarria, Andrea Ramos Serrano, Ichiro Hirao, Anthony J. Berdis

Chemistry Faculty Publications

O6-methylguanine is a miscoding DNA lesion arising from the alkylation of guanine. This report uses the bacteriophage T4 DNA polymerase as a model to probe the roles hydrogen-bonding interactions, shape/size, and nucleobase desolvation during the replication of this miscoding lesion. This was accomplished by using transient kinetic techniques to monitor the kinetic parameters for incorporating and extending natural and non-natural nucleotides. In general, the efficiency of nucleotide incorporation does not depend on the hydrogen-bonding potential of the incoming nucleotide. Instead, nucleobase hydrophobicity and shape complementarity appear to be the preeminent factors controlling nucleotide incorporation. In addition, shape complementarity plays a …

Rna Oxidation Adducts 8-Ohg And 8-Oha Change With Aβ42 Levels In Late-Stage Alzheimer's Disease, Adam M. Weidner, Melissa A. Bradley, Tina L. Beckett, Dana M. Niedowicz, Amy L.S. Dowling, Sergey V. Matveev, Harry Levine, Mark A. Lovell, M. Paul Murphy

Sanders-Brown Center on Aging Faculty Publications

While research supports amyloid-β (Aβ) as the etiologic agent of Alzheimer's disease (AD), the mechanism of action remains unclear. Evidence indicates that adducts of RNA caused by oxidation also represent an early phenomenon in AD. It is currently unknown what type of influence these two observations have on each other, if any. We quantified five RNA adducts by gas chromatography/mass spectroscopy across five brain regions from AD cases and age-matched controls. We then used a reductive directed analysis to compare the RNA adducts to common indices of AD neuropathology and various pools of Aβ. Using data from four disease-affected brain …

The Nucleotide Exchange Factor Ric-8a Is A Chaperone For The Conformationally Dynamic Nucleotide-Free State Of G Alpha I1, Celestine J. Thomas, Klara Briknarova, Jonathan K. Hilmer, Navid Movahed, Brian Bothner, John P. Sumida, Gregory G. Tall, Stephen R. Sprang

Chemistry and Biochemistry Faculty Publications

Heterotrimeric G protein alpha subunits are activated upon exchange of GDP for GTP at the nucleotide binding site of G alpha, catalyzed by guanine nucleotide exchange factors (GEFs). In addition to transmembrane G protein-coupled receptors (GPCRs), which act on G protein heterotrimers, members of the family cytosolic proteins typified by mammalian Ric-8A are GEFs for Gi/q/12/13-class G alpha subunits. Ric-8A binds to G alpha.GDP, resulting in the release of GDP. The Ric-8A complex with nucleotide-free G alpha i1 is stable, but dissociates upon binding of GTP to G alpha i1. To gain insight into the mechanism of Ric-8A-catalyzed GDP release …

Group 11 Metal Compounds With Tripodal Bis(Imidazole) Thioether Ligands. Applications As Catalysts In The Oxidation Of Alkenes And As Antimicrobial Agents, Fangwei Liu, Reema Anis, Eunmi Hwang, Rafael Ovalle, Armando Varela-Ramírez, Renato J. Aguilera, María Contel

Publications and Research

New group 11 metal complexes have been prepared using the previously described tripodal bis(imidazole) thioether ligand (N-methyl-4,5-diphenyl-2- imidazolyl)2C(OMe)C(CH3)2S(tert-Bu) ({BITOMe,StBu}, 2). The pincer ligand offers a N2S donor atom set that can be used to coordinate the group 11 metals in different oxidation states [AuI , AuIII, AgI , CuI and CuII]. Thus the new compounds [Au{BITOMe,StBu}Cl][AuCl4]2 (3), [Au{BITOMe,StBu}Cl] (4), [Ag{BITOMe,StBu}X] (X = OSO2CF3 - 5, PF6 - 6) and [Cu{BITOMe,StBu}Cl2] (7) have been synthesized from reaction of 2 with the appropriate metal precursors, and characterized in solution. While attempting characterization in the solid state of 3, single crystals of the …

Thermal-Initiated Hydroxyethyl Methacrylate Functionalization Of Multiwalled Carbon Nanotubes, Greg Curtzwiler, Philip Costanzo, Ray Fernando, Jeffrey E. Danes, Keith Vorst

Chemistry and Biochemistry

Multiwalled-carbon nanotubes (MWCNTs) were functionalized via thermoinitiated free radical polymerization of 2-hydroxyethyl methacrylate (HEMA) using benzoyl peroxide. Tip sonication was used during the polymerization reaction to separate agglomerated nanotubes. The functionalization was confirmed by control experiments and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). Differential scanning calorimetry indicated that the addition of poly(HEMA)-MWCNTs to a two-component polyurethane coating will have little effect on the glass transition temperature of the coating. The poly(HEMA)-functionalized MWCNTs formed large colloidal structures of highly dispersed nanotubes in both the nonsheared and sheared coatings as determined by atomic force microscopy. This study determined a quick …

Quantifying The Flux Of Caco3 And Organic Carbon From The Surface Ocean Using In Situ Measurements Of O-2, N-2, Pco(2), And Ph, Steven Emerson, Christopher Sabine, Meghan F. Cronin, Richard Feely, Sarah E. Cullison Gray, Michael Degrandpre

Chemistry and Biochemistry Faculty Publications

Ocean acidification from anthropogenic CO2 has focused our attention on the importance of understanding the rates and mechanisms of CaCO3 formation so that changes can be monitored and feedbacks predicted. We present a method for determining the rate of CaCO3 production using in situ measureme nts of fCO(2) and pH in surface waters of the eastern subarctic Pacific Ocean. These quantities were determined on a surface mooring every 3 h for a period of about 9 months in 2007 at Ocean Station Papa (50 degrees N, 145 degrees W). We use the data in a simple surface ocean, mass balance …

Co2 Production In The Bromate-1,4-Cyclohexanedione Oscillatory Reaction, Jiamin Feng, James R. Green, Samuel A. Johnson, Jichang Wang

Chemistry and Biochemistry Publications

NMR and GC/MS spectroscopy of the organic extracts of the oscillatory bromate-1,4-cyclohexanedione reaction illustrate the presence of ring-opening products 5-(dibromomethylene)-2(5H)-furanone, (E)-5,5,5-tribromo-4-oxo-2-pentenoic acid, and dibromoacetic acid, particularly at elevated temperatures. The loss of a carbon atom from the six-membered ring after ring opening led to gas formation and such a process became more vigorous at >60 °C, with the direct observation of bubbles in a stirred batch reactor. Gravimetric experiments confirm that the amount of carbon dioxide gas produced increases rapidly with reaction temperature. Parallel experiments suggest that the ring-opening process involves the oxidation of brominated benzoquinones by bromate. Copyright © …

Direct Imaging Of Two-State Dynamics On The Amorphous Silicon Surface, S. Ashtekar, Gregory E. Scott, J. Lyding, M. Gruebele

Chemistry and Biochemistry

Amorphous silicon is an important material, amidst a debate whether or not it is a glass. We produce amorphous Si surfaces by ion bombardment and vapor growth, and image discrete Si clusters which hop by two-state dynamics at 295 K. Independent of surface preparation, these clusters have an average diameter of ~5 atoms. Given prior results for metallic glasses, we suggest that this cluster size is a universal feature. The hopping activation free energy of 0.93 ± 0.15 eV is rather small, in agreement with a previously untested surface glass model. Hydrogenation quenches the two-state dynamics, apparently by increasing surface …

Lipid Peroxidation And Neurodegenerative Disease, Tanea Reed

Chemistry Faculty and Staff Scholarship

Lipid peroxidation is a complex process involving the interaction of oxygen-derived free radicals with polyunsaturated fatty acids, resulting in a variety of highly reactive electrophilic aldehydes. Since 1975, lipid peroxidation has been extensively studied in a variety of organisms. As neurodegenerative diseases became better understood, research establishing a link between this form of oxidative damage, neurodegeneration, and disease has provided a wealth of knowledge to the scientific community. With the advent of proteomics in 1995, the identification of biomarkers for neurodegenerative disorders became of paramount importance to better understand disease pathogenesis and develop potential therapeutic strategies. This review focuses on …

Tension Directly Stabilizes Reconstituted Kinetochore-Microtubule Attachments, Bungo Akiyoshi, Krishna K. Sarangapani, Andrew F. Powers, Christian R. Nelson, Steve Reichow, Hugo Arellano-Santoyo, Tamir Gonen, Jeffrey A. Ranish, Charles L. Asbury, Sue Biggins

Chemistry Faculty Publications and Presentations

Kinetochores are macromolecular machines that couple chromosomes to dynamic microtubule tips during cell division, thereby generating force to segregate the chromosomes. Accurate segregation depends on selective stabilization of correct ‘bi-oriented’ kinetochore-microtubule attachments, which come under tension due to opposing forces exerted by microtubules. Tension is thought to stabilize these bi-oriented attachments indirectly, by suppressing the destabilizing activity of a kinase, Aurora B. However, a complete mechanistic understanding of the role of tension requires reconstitution of kinetochore-microtubule attachments for biochemical and biophysical analyses in vitro. Here we show that native kinetochore particles retaining the majority of kinetochore proteins can be …

Applications Of Argentation Solid Phase Extraction To The Capsaicinoids: Purification Of Commercial Standards And Isolation Of Homodihydrocapsaicin (8-Methyl) From 'Bhut Jolokia', Robert Q. Thompson, Kathleen Loa

Faculty & Staff Scholarship

Argentation solid phase extraction was employed to purify commercial standards of capsaicin (6-ene-8-methyl) and dihydrocapsaicin (8-methyl). The purity was improved from 96.7% to 99.6% and from 89% to 96%, respectively, with 75% and 60% yield, respectively. Reversed phase solid phase extraction, argentation solid phase extraction, and preparative liquid chromatography with a C30 phase were used to isolate capsaicinoids from the fruits of 'Bhut Jolokia' peppers. The compounds capsaicin (6-ene-8-methyl) and dihydrocapsaicin (8-methyl) comprised 74% and 21% of the total mass of capsaicinoids. respectively. The remaining 5% of the capsaicinoids mass included the compounds: nordihydrocapsaicin (7-methyl), N-vanillylnonanamide, two homocapsaicin isomers, N-vanillyldecanamide, …

The Exonuclease Activity Of Hpmc2 Is Required For Transcriptional Regulation Of The Qr Gene And Repair Of Estrogen-Induced Abasic Sites, N. Krishnamurthy, C. R. Ngam, Anthony J. Berdis, M. M. Montano

Chemistry Faculty Publications

We have previously reported that the expression of antioxidative stress enzymes is upregulated by trans-hydroxytamoxifen (TOT) in breast epithelial cell lines providing protection against estrogen-induced DNA damage. This regulation involves Estrogen Receptor β (ERβ) recruitment to the Electrophile Response Element (EpRE) and a novel protein, human homolog of Xenopus gene which Prevents Mitotic Catastrophe (hPMC2). We have also demonstrated that ERβ and hPMC2 are required for TOT-dependent recruitment of poly (ADP-ribose) polymerase 1 (PARP-1) and Topoisomerase IIβ (Topo IIβ) to the EpRE. Sequence analysis reveals that the C-terminus of hPMC2 encodes a putative exonuclease domain. Using in vitro kinetic assays, …

Pcr Amplification Of Trypanosoma Cruzi - Specific Dna From Raccoon Blood Samples, Colin Moss

Mahurin Honors College Capstone Experience/Thesis Projects

The parasitic protist Trypanosoma cruzi is the causative agent of Chagas Disease. Chagas Disease causes greater than 15,000 deaths each year, and nearly 28 million people are believed to be at risk of infection in Central and South America. This parasite has been described in many mammalian host species and has also been described in the United States. The purpose of this study was to attempt to use PCR to amplify T. cruzi-specific DNA directly from blood samples obtained from raccoons (Procyon lotor) trapped in Warren and Barren Counties of Kentucky in 2007 and 2008. DNA was …

Assessing Social Benefits Of Domestic Rainwater Harvesting In Southern Kenya, Lindsey M. Filiatreau

Mahurin Honors College Capstone Experience/Thesis Projects

In the Kasigau location of the Voi District of Kenya, severe rainwater shortages closed fourteen water collection stations in 2008 and 2009, leaving ten water sources to service 15,000 people in the region. Few families in the area have domestic rainwater harvesting systems which are an easily implemented, low-cost means of water collection. I investigated the ability of rainwater catchment systems to modify family time budgets (by reducing water collection time) and lessen the severity of water scarcity (by supplying families a significant amount of water). Forty families participated in the research, 20 of whom received free installation of a …

The Proliferation Of Vascular Smooth Muscle Cells Depends On Thioredoxin 1 Protein In A Model Of Pulmonary Hypertension, Viktoria Nelin

Mahurin Honors College Capstone Experience/Thesis Projects

Pulmonary hypertension (PH) is a disease which manifests itself in the lungs of both adults and children. Vascular proliferation and remodeling are the hallmarks of PH and are found mainly in the pulmonary arterial smooth muscle cells (PASMC). The cause of PASMC proliferation and vascular remodeling in PH is poorly understood. Hypoxia, or low oxygen content, underlies many forms of PH. Hypoxia results in alterations in the redox balance of the PASMC. Therefore, the aim of this study was to examine the role of the thioredoxin system, an antioxidant system in the cell, in hypoxia-induced proliferation in PASMC. Protein was …

Screening Rnai Transformants Of Chlamydomonas For Reduced Expression Of The Photoreceptor Cryptochrome, Jeremy Webb

Mahurin Honors College Capstone Experience/Thesis Projects

Chlamydomonas reinhardtii is a unicellular green alga. In C. reinhardtii, three types of photoreceptors are known to be present: rhodopsins, phototropins, and cryptochromes. The single cryptochrome is the most likely photoreceptor for adjusting the circadian clock to the daily light/dark cycles, because cryptochromes are involved in clock entrainment in higher plants and insects. In this segment of the research, C. reinhardtii strains, which were genetically modified through transformation with a RNA interference construct, were screened for reduction in cryptochrome compared to the control strain. After C. reinhardtii cultures were harvested in complete darkness, all soluble proteins were extracted from the …

Dna Sequence Variation In The Wingless Gene Product In Buckeye Butterflies (Genus Junonia), Bonnie Mccullagh

Mahurin Honors College Capstone Experience/Thesis Projects

Wingless is a highly conserved gene important to cell determination in development. In Drosophila, the wingless gene product has been identified as responsible for wing patterning. In Bicyclus anynana and Junonia coenia, wingless gene product is expressed in a fashion that suggests that it is involved in butterfly wing color pattern development. The wingless gene product has been implicated as a potential focal signal for patterning the eyespot of Junonia butterflies. I have shown that extensive DNA sequence variation (26.04% of the sequenced region) exists in 402 bp of wingless coding sequence among 338 specimens of Junonia from …

Assessment Of Prenatal Care And Perinatal Outcomes In Kasigau, Kenya, Allison Smith

Mahurin Honors College Capstone Experience/Thesis Projects

The World Health Organization (WHO) implemented the Millennium Declaration in 2000 to establish global health goals to be achieved by 2015. Two of these Millennium Development Goals (MDG’s) are directly related to maternal, neonatal and child health. Healthcare during the prenatal period can help achieve the WHO MDG’s for maternal health and child mortality. Evidence has shown that women in Kenya have limited access to prenatal care. This study focused on the prenatal care and postnatal outcome trends of the women in Kasigau, Kenya. Participants were surveyed in three villages (Rukanga, Makwasinyi, and Bhuguta) to determine if prenatal care was …

Human-Wildlife Conflict On Small, Subsistence Farms In Kenya, Christopher B. Colonna

Mahurin Honors College Capstone Experience/Thesis Projects

As human populations expand, wildlife suddenly competes with humans for resources and confrontation arises as a result. Rural Africa is typical of this problem. We surveyed local owners of small farms within the five villages surrounding Mount Kasigau in Southeast Kenya to quantify losses due to wildlife depredation on both subsistence and cash crops as well as to discover the patterns and variables influencing farmer-wildlife confrontations in the region. We found no statistically significant correlations among the value of damage per acre, the distance from the bush, or the distance to the nearest water source. We did find statistical significance …

Effective And Affordable Novel Arsenic Removal Technology, Benadin Varajic

Mahurin Honors College Capstone Experience/Thesis Projects

Arsenic contaminated drinking water is a serious worldwide issue faced by millions of people every day. Long term exposure to arsenic levels above the World Health Organization’s (WHO) standard of 10 ppb has been associated with severe detrimental health effects including cardiovascular disease and cancer. Although current water purification technologies exist, their implementation is an unrealistic goal by many third world nations for a variety of reasons, the most common being the cost associated with what are typically complicated procedures. This study strives to discover an effective and affordable novel arsenic removal technology.

The first step of this study was …

Characterization Of Ceriporiopsis Subvermispora Bicupin Oxalate Oxidase Expressed In Pichia Pastoris, Patricia Moussatche, Alexander Angerhofer, Witcha Imaram, Eric Hoffer, Kelsey Uberto, Christopher Brooks, Crystal Bruce, Daniel Sledge, Nigel G. J. Richards, Ellen W. Moomaw

Faculty and Research Publications

Oxalate oxidase (E.C. 1.2.3.4) catalyzes the oxygen-dependent oxidation of oxalate to carbon dioxide in a reaction that is coupled with the formation of hydrogen peroxide. Although there is currently no structural information available for oxalate oxidase fromCeriporiopsis subvermispora (CsOxOx), sequence data and homology modeling indicate that it is the first manganese-containing bicupin enzyme identified that catalyzes this reaction. Interestingly, CsOxOx shares greatest sequence homology with bicupin microbial oxalate decarboxylases (OxDC). We show that CsOxOx activity directly correlates with Mn content and other metals do not appear to be able to support catalysis. EPR spectra indicate that the Mn is present …

An Assessment Of Stable Hydrogen-Isotope Analysis Methods To Assign Geographic Origin To Migratory Red-Tailed Hawks (Buteo Jamaicensis), Carla Marie Ahlschwede

Department of Environmental Studies: Undergraduate Student Theses

Stable-hydrogen isotopes are becoming an increasingly popular method of studying migratory birds, though sample preparation methods may affect results. In this study I examined feathers from red-tailed hawks (Buteo jamaicensis) to determine the relationship between measure of δD due to inter-feather variation or drying methods, assessed the accuracy of results by using two birds of known-origin and estimated possible natal origins of migratory red-tailed hawks. Two feathers per individual were taken from 81 wild hawks caught at Hitchcock Nature Center near Crescent IA and from 2 rescued red-tailed hawks, Raptor Recovery Nebraska near Eagle, NE. 119 of the …

Testing The Potential Of Using Fungi To Convert Human Waste Into Protein, Alex Zapata, Elizabeth Phillippi, Blair Mitchell, Jon Schoer, Michael Watters

Symposium on Undergraduate Research and Creative Expression (SOURCE)

We report on the results of a pilot experiment designed to test the potential of filamentous fungi (mold) to reduce solid waste (feces) while converting it into a consumable, high protein food product. Feces represent an untapped resource. Filamentous fungi are natural decomposers with the ability to use this resource. Many filamentous fungi are safe to eat. We examined growth in order to determine the conditions which maximized the rate of conversion of solid waste into fungal biomass. For this pilot, we compared the effect of different lengths of incubation, different methods of aeration, and different available surface area. The …

Impacts Of The Species Elaeagnus Umbellate On The Soil And Water Quality Of The Pierce Cedar Creek Institute Ecosystem, Yacoub Aljobeh, Kristin Engerer

Symposium on Undergraduate Research and Creative Expression (SOURCE)

The species Elaeagnus umbellate, more commonly known as autumn olive, is a shrub that is invasive to the United States and indigenous to East Asia. Even though the autumn olive is not native to North America, it was able to thrive and adapt to the new environment by using its ability to fix nitrogen. Nitrogen-fixing is a process where plants intake molecular nitrogen from the atmosphere and convert it into other forms of nitrogen that can be used by the plants. One of the nitrogen-fixing by-products is nitrate. Excessive amounts of nitrate can easily leach from the plant’s root …

Epistatic Roles For Pseudomonas Aeruginosa Muts And Dinb (Dna Pol Iv) In Coping With Reactive Oxygen Species-Induced Dna Damage, Laurie H. Sanders, Babho Devadoss, Geraldine V. Raja, Jaime O'Connor, Shengchang Su, Daniel J. Wozniak, Daniel J. Hassett, Anthony J. Berdis, Mark D. Sutton

Chemistry Faculty Publications

Pseudomonas aeruginosa is especially adept at colonizing the airways of individuals afflicted with the autosomal recessive disease cystic fibrosis (CF). CF patients suffer from chronic airway inflammation, which contributes to lung deterioration. Once established in the airways, P. aeruginosa continuously adapts to the changing environment, in part through acquisition of beneficial mutations via a process termed pathoadaptation. MutS and DinB are proposed to play opposing roles in P. aeruginosa pathoadaptation: MutS acts in replication-coupled mismatch repair, which acts to limit spontaneous mutations; in contrast, DinB (DNA polymerase IV) catalyzes error-prone bypass of DNA lesions, contributing to mutations. As part of …

Dicarbonyldichloridobis(Trimethylphosphane)Iron(Ii)–Carbonyldichloridotris(Trimethylphosphane)Iron(Ii)–Tetrahydrofuran (1/1/2), Nigam Rath, Meghan Stouffer, Matthew Janssen, John Bleeke

Chemistry & Biochemistry Faculty Works

The asymmetric unit of the title crystal, [FeCl2(C3H9P)3(CO)]·[FeCl2(C3H9P)2(CO)2]·2C4H8O, contains half mol­ecules of the two closely related FeII complexes lying on mirror planes and a tetra­hydro­furan solvent mol­ecule, one C atom of which is disordered over two sets of sites with site occupancy factors 0.633 (9) and 0.367 (9). In both FeII complex mol­ecules, a distorted octa­hedral coordination geometry has been observed around the Fe atoms. Weak intermolecular C-H...O inter­actions are observed in the crystal structure.

Dehydrotropylium-Co2(Co)6 Ion. Generation, Reactivity And Evaluation Of Cation Stability, Sheida Amiralaei, James Gauld, James R. Green

Chemistry and Biochemistry Publications

The dehydrotropylium–Co₂(CO)₆ ion was generated by the action of HBF₄ or BF₃⋅OEt₂ on the corresponding cycloheptadienynol complex, which in turn has been prepared in four steps from a known diacetoxycycloheptenyne complex. The reaction of the cycloheptadienynol complex via the dehydrotropylium–Co₂(CO)₆ ion with several nucleophiles results in substitution reactions with reactive nucleophiles (N>1) under normal conditions, and a radical dimerisation reaction in the presence of less reactive nucleophiles. Competitive reactions of the cycloheptadienynol complex with an acyclic trienynol complex show no preference for generation of the dehydrotropylium–Co_{2 …}

Synthesis Of ‘Spacer’-Naproxen [2-(6-Methoxybiphenylen-2-Yl)Propanoic Acid] And -Isonaproxen [2-(7-Methoxybiphenylen-2-Yl)Propanoic Acid], Juan A. González Gómez, James R. Green, Peter C. Vollhardt

Chemistry and Biochemistry Publications

The CpCo(CO)₂-catalyzed cocyclization of 1,2-diethynyl- 4-methoxybenzene with alkynes can be applied to the synthesis of ‘spacer’-naproxen [2-(6-methoxybiphenylen-2-yl)propanoic acid] and its 7-methoxy isomer, ‘spacer’-isonaproxen. While unsymmetrical alkynes are incorporated without regioselectivity, the methoxy group in 6-methoxy-2,3-bis(trimethylsilyl)biphenylene directs electrophiles to C-3, thus allowing for regiochemical differentiation between the 2- and 3-positions.