Investigation Of Z/E Configurational Isomerization In Dicyanorhodanine-Functionalized Oligothiophenes
Lei Li,1 Asmerom O. Weldeab,1 Cory T. Kornman,1 and Ronald K. Castellano1
1 Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, FL 32611-7200, USA
Oligothiophenes functionalized with the dicyanorhodanine acceptor have been widely used as electron donor materials in organic solar cells, where they have led to state-of-the-art device performance. Surprisingly, there are no reports in this literature that has considered potential configurational isomerization (Z to E) within the acceptor portion that could potentially alter electronics, conformational preferences, or molecular packing. Reported here is the preliminary investigation of Z/E configurational isomerization in a homologous series of oligothiophenes terminated with the dicyanorhodanine group. The structures of the two configurational isomers were first confirmed by 2D NMR (gHMBC and EXSIDE), and their gas-phase stabilities were studied through DFT calculation. The origin of the isomerization and the consequences of the structural change on optical properties have been explored. By varying the π-conjugation length, solubilizing groups, solvent, and photon source, some of the factors that influence the Z/E configurational isomerization have been identified. The kinetics of the processes and consequences of the isomerization on thin film processing and structure are currently being evaluated.
Iodine catalyzed diazo activation to access radical reactivity
Chiyu Wei, Pan Li, Xiaodong Shi*
Univerisity of South Florida
An unprecedented iodine catalyzed diazo activation is disclosed herein under either photo- or thermal-initiated conditions. The mechanistic studies revealed the formation of an iodo-substituted alkyl radical as the key intermediate, which represents a novel approach to enable diazo radical reactivity. This metal-free diazo-activation strategy was successfully applied to olefin cyclopropanation with excellent yields. A further extension to substituted pyrrole synthesis under thermal-initiated conditions demonstrates the unique reactivity using this method over typical metal-catalyzed conditions.
Development of the reductive enyne Cope rearrangement
Sarah K. Scott, Katherine E. White and Alexander J. Grenning
Department of Chemistry, University of Florida, Gainesville FL 32611-7200, USA
Although the enyne Cope rearrangement has been known for several decades, it has not seen applications in synthetic chemistry due to low yields and product instability. However, through the implementation of a reductive variant, this reaction is now being exploited to access functionalized allenyl malonates, which can be further manipulated to generate a range of carbocyclic frameworks commonly found in natural products. This work not only demonstrates the first potential application of the enyne Cope rearrangement in the synthesis of natural products and their analogs, but also provides significant insight into overcoming the challenges previously associated with the transformation.
NSF 101: The Process of Preparing, Submitting, and Reviewing Proposals for The National Science Foundation
National Science Foundation and the University of Colorado
The process of preparing, submitting, and reviewing proposals for Chemistry Division of The National Science Foundation (NSF) will be described. This talk is geared at those in early stages of their careers and will provide some basic advice about the process of obtaining funding from the NSF.
Green Methods for the Synthesis of Anti-Cancer Resveratrol Analogues
Daniel H. Paull
Florida Gulf Coast University
Resveratrol analogues have been widely tested in all kinds of aging-related disorders in the last decade, and their use has only increased because of successes in several diverse areas, including anti-inflammatory, cardioprotective, and anti-cancer. Likewise, we need an ever-expanding library of synthetic methods for their production, especially ones that are easy, quick, efficient, and clean. These green principles guide our method development, and we have three distinct methods to present.
The products we synthesize are tested against various breast cancer cell lines, and we have found several that are active against, and induce metastasis-inhibiting morphological changes in, triple-negative breast cancer cell lines. We are currently designing and synthesizing a second, more focused set of compounds for testing. This application will be presented along with the advantages of each green method for these syntheses.
Synthesis and Biological Evaluation of Spirastrellolide A analogues
Jagadeesh Nagendra Manda, Barry B. Butler Jr, and Aaron Aponick
University of Florida
Spirastrellolide A is a marine macrolide first isolated by the Anderson group from the Caribbean marine sponge Spirastrella coccinea in 2003. Due to its novel antimitotic potency (IC50 = 100 ng/mL) and selective inhibition of protein phosphatase 2A (IC50 = 1 nM), Spirastrellolide A is potentially a lead compound for anti-cancer therapeutics. However, further evaluation of its biological potency was hindered by inadequate supplies. This issue could be circumvented by developing structurally simplified analogues of Spirastrellolide A that could retain the biological activity. A convergent synthesis of southern hemisphere of spirastrellolide A which involved two key intermediates including a tetrahydropyran and a [6,6]-spiroketal was designed. Two gold-catalyzed cyclization methods developed in our group were employed in the synthesis, namely 1) Gold-catalyzed dehydrative cyclization of monoallylic diols for the synthesis of the tetrahydropyran, and 2) Regioselective gold-catalyzed spiroketalization for the efficient generation of the [6,6]-spiroketal. Progress towards the synthesis of Spirastrellolide A analogues will be presented.
Catalytic Activation of Diazonium and Diazo Compounds: New Chemistry from Unexpected Results
Department of Chemistry, University of South Florida
Activation and transformations of organic compounds is the main goal for organic chemists. Various activation strategy might give different intermediate, leading to distinct transformations. Dazonium and diazo compounds were active motifs containing two nitrogen atoms. Releasing of nitrogen gas is an entropic gaining and irreversible process which makes dazonium and diazo compounds wildly used in organic synthesis.
By utilizing gold catalyst, our group developed a diazoester decomposition forming a carbophilic carbocation for Friedel–Crafts alkylation. With this result, we further wanted to merge photoredox and gold catalyst together to activate diazonium salt. Surprisingly, photoredox catalyst was not necessary in the transformation, which suggested that gold catalyst itself could also serve as a redox catalyst between Au(I) and Au (III). Unexpectedly, we developed iodide activation of diazo compounds to form iodocaboradical.