Construction of the Tetracyclic Core of the Lycopodium Alkaloid Annotinolide C

2021 ◽  
Author(s):  
Xiang Guo ◽  
Yong-Yao Li ◽  
Shuang-Hu Wang ◽  
Fu-Min Zhang ◽  
Baosheng Li ◽  
...  
Keyword(s):  
Lycopodium Alkaloid ◽  
Semipinacol Rearrangement ◽  
Tetracyclic Core ◽  
Key Steps

A concise method of synthesizing the tetracyclic core of annotinolide C has been developed. The key steps feature a tandem epoxidation/semipinacol rearrangement step to construct an aza quaternary aza [6.5]...

Formal Synthesis of Actinoranone Using a Racemization-Free One-Pot Semipinacol Rearrangement/Wittig Reaction

2018 ◽  
Author(s):  
Martina Menger ◽  
Mathias Christmann
Keyword(s):  
Natural Product ◽  
Wittig Reaction ◽  
Reaction Sequence ◽  
One Pot ◽  
Formal Synthesis ◽  
Linear Sequence ◽  
Semipinacol Rearrangement ◽  
Key Steps

Here, we report a formal synthesis of the marine cytotoxic meroterpenoid actinoranone. Key steps include a racemization-free semipinacol rearrangement/Wittig reaction sequence and a chiral pool approach for the syntheses of the tetralone and the decalin fragments, respectively. The presented route provides access to the natural product in 14 steps in the longest linear sequence.

scholarly journals Construction of the [6-7-5-5] tetracyclic core of all the carbocyclic frameworks of yuzurimine-type alkaloids

2015 ◽  
Vol 51 (58) ◽  
pp. 11568-11571 ◽  
Author(s):  
Ichiro Hayakawa ◽  
Keisuke Niida ◽  
Hideo Kigoshi
Keyword(s):  
Wittig Reaction ◽  
Intramolecular Wittig Reaction ◽  
Tetracyclic Core ◽  
Key Steps

Construction of the [6-7-5-5] tetracarbocyclic core of yuzurimine-type alkaloids was achieved by using a unique in situ intramolecular Wittig reaction and Sm-mediated cyclization as key steps.

Construction of the [6,5,7,5] Tetracyclic Core of Calyciphylline A Type Alkaloids via a Tandem Semipinacol Rearrangement/Nicholas Reaction

2017 ◽  
Vol 19 (17) ◽  
pp. 4648-4651 ◽  
Author(s):  
Hui Shao ◽  
Wen Bao ◽  
Ze-Ran Jing ◽  
Yun-Peng Wang ◽  
Fu-Min Zhang ◽  
...  
Keyword(s):  
Nicholas Reaction ◽  
Semipinacol Rearrangement ◽  
Tetracyclic Core

Total Syntheses of (–)-Alstolucines A, B, and F, (–)-Echitamidine, and (–)-N-Demethylalstogucine

Synthesis ◽  
2015 ◽  
Vol 47 (11) ◽  
pp. 1547-1556 ◽  
Author(s):  
Christiana Teijaro ◽  
Senzhi Zhao ◽  
Praveen Kokkonda ◽  
Rodrigo Andrade
Keyword(s):  
Heck Reaction ◽  
Second Generation ◽  
One Pot ◽  
Total Syntheses ◽  
Tetracyclic Core ◽  
Key Steps ◽  
First And Second Generation ◽  
Intramolecular Heck Reaction

The first enantioselective total syntheses of (–)-alstolucinces A, B, and F, (–)-echitamidine, and (–)-N-demethylalstogucine are reported. This article details the development of our first- and second-generation approaches toward the ABCE tetracyclic core of the strychnos alkaloids and the application thereof to the aforementioned targets. Key steps involve our sequential one-pot biscyclization method that constructs the C and E rings of the tetracyclic core and Rawal’s application of the intramolecular Heck reaction to secure the pentacyclic framework common amongst all targets.

Formal Synthesis of Actinoranone Using a Racemization-Free One-Pot Semipinacol Rearrangement/Wittig Reaction

2018 ◽  
Author(s):  
Martina Menger ◽  
Mathias Christmann
Keyword(s):  
Natural Product ◽  
Wittig Reaction ◽  
Reaction Sequence ◽  
One Pot ◽  
Formal Synthesis ◽  
Linear Sequence ◽  
Semipinacol Rearrangement ◽  
Key Steps

Here, we report a formal synthesis of the marine cytotoxic meroterpenoid actinoranone. Key steps include a racemization-free semipinacol rearrangement/Wittig reaction sequence and a chiral pool approach for the syntheses of the tetralone and the decalin fragments, respectively. The presented route provides access to the natural product in 14 steps in the longest linear sequence.

Reflections on the Cognitive Interviewing Reporting Framework

Methodology ◽  
2013 ◽  
Vol 9 (3) ◽  
pp. 123-128 ◽  
Author(s):  
Gordon Willis ◽  
Hennie Boeije
Keyword(s):  
Research Design ◽  
Cognitive Testing ◽  
Level Of Detail ◽  
Cognitive Interviewing ◽  
Research Groups ◽  
Research Project ◽  
Reporting Framework ◽  
Full Explanation ◽  
Key Steps

Based on the experiences of three research groups using and evaluating the Cognitive Interviewing Reporting Framework (CIRF), we draw conclusions about the utility of the CIRF as a guide to creating cognitive testing reports. Authors generally found the CIRF checklist to be usable, and that it led to a more complete description of key steps involved. However, despite the explicit direction by the CIRF to include a full explanation of major steps and features (e.g., research objectives and research design), the three cognitive testing reports tended to simply state what was done, without further justification. Authors varied in their judgments concerning whether the CIRF requires the appropriate level of detail. Overall, we believe that current cognitive interviewing practice will benefit from including, within cognitive testing reports, the 10 categories of information specified by the CIRF. Future use of the CIRF may serve to direct the overall research project from the start, and to further the goal of evaluation of specific cognitive interviewing procedures.

The development of alternative energy sources: Prospects in Russia and the world

2020 ◽  
Vol 16 (5) ◽  
pp. 885-904
Author(s):  
M.E. Frai
Keyword(s):  
Alternative Energy ◽  
Systems Approach ◽  
Energy Resource ◽  
Current Situation ◽  
Energy Sources ◽  
The Sustainable Development ◽  
Energy Complex ◽  
Alternative Energy Sources ◽  
Governmental Institutions ◽  
Key Steps

Subject. The article discusses limited sources of energy nowadays and an ongoing survey of new ones. I focus on fuel and energy complexes worldwide and in Russia. Objectives. The study is to analyze the future use of alternative energy sources in the fuel and energy complex nationwide and worldwide. I review the existing energy sources of the fuel and energy complex in the global and regional markets, specifically the alternative ones. Methods. The study relies upon methods of statistics, analysis and systems approach. Results. The article demonstrates that the fuel and energy complex strongly depends on the current situation in the energy resource market, which is difficult to forecast. If we continue relying on traditional energy resources, we get exposed to some risks affecting the sustainable development of the economy. Russia should diversify the power engineering sector by developing alternative energy sources. The article sets forth the economic rationale for alternative sources and key steps Russia shall make. Conclusions and Relevance. Considering the current situation in the energy balance, alternative energy is what any advanced society seeks for, being supported by manufacturers, governmental institutions, and researchers, though low profitability and high infrastructure costs impede its development. In Russia, these challenges are even more palpable. However, even now Russia is able to find alternative energy solutions. In addition to advantages of alternative energy, which is globally proclaimed, they will also help Russia diversify and update the economic system.

Synthesis of Spongidine A, D and Petrosaspongiolide L Methyl Ester Using Pyridine C-H Functionalization

2019 ◽  
Author(s):  
Florian Bartels ◽  
Manuela Weber ◽  
Mathias Christmann
Keyword(s):  
Natural Products ◽  
Methyl Ester ◽  
Hydrogen Atom ◽  
Phospholipase A2 ◽  
Late Stage ◽  
Hydrogen Atom Transfer ◽  
Ring System ◽  
Tetracyclic Core ◽  
Intramolecular Hydrogen ◽  
Phospholipase A2 Inhibitors

<div>An efficient strategy for the synthesis of the potent phospholipase A2 inhibitors spongidine A and D is presented. The tetracyclic core of the natural products was assembled via an intramolecular hydrogen atom transfer‐initiated Minisci reaction. A divergent late‐stage functionalization of the tetracyclic ring system was also used to achieve a concise synthesis of petrosaspongiolide L methyl ester.</div>

CO2 Activation on Heterostructures of Bi2O3-Nanocluster Modified TiO2: Promoting the Critical First Step in CO2 Conversion

2018 ◽  
Author(s):  
Michael Nolan
Keyword(s):  
Metal Oxide ◽  
Density Functional ◽  
Initial Step ◽  
Difficult Problem ◽  
Carbonate Formation ◽  
Structural Distortions ◽  
Strong Adsorption ◽  
Two Factors ◽  
Key Steps ◽  
Recent Experimental Work

The conversion of CO<sub>2</sub> to fuels is of significant importance in enabling the production of sustainable fuels, contributing to alleviating greenhouse gas emissions. While there are a number of key steps required to convert CO<sub>2</sub>, the initial step of adsorption and activation by the catalyst is critical. Well-known metal oxides such as oxidised TiO<sub>2</sub> or CeO<sub>2</sub> are unable to promote this step. In addressing this difficult problem, recent experimental work shows the potential for bismuth-containing materials to activate and convert CO<sub>2</sub>, but the origin of this activity is not yet clear. Additionally, nanostructures can show enhanced activity towards CO<sub>2</sub>. In this paper we present density functional theory (DFT) simulations of CO<sub>2</sub> activation on heterostructured materials composed of extended rutile and anatase TiO<sub>2</sub> surfaces modified with nanoclusters with Bi<sub>2</sub>O<sub>3</sub> stoichiometry. These heterostructures show low coordinated Bi sites in the nanoclusters and a valence band edge that is dominated by Bi-O states. These two factors mean that supported Bi<sub>2</sub>O<sub>3</sub> nanoclusters are able to adsorb and activate CO<sub>2</sub>. Computed adsorption energies lie in the range of -0.54 eV to -1.01 eV. In these strong adsorption modes, CO<sub>2</sub> is activated, in which the molecule bends giving O-C-O angles of 126 - 130<sup>o</sup> and elongation of C-O distances up to 1.28 Å, with no carbonate formation. The electronic properties show a strong CO<sub>2</sub>-Bi-oxygen interaction that drives the interaction of CO<sub>2</sub> to induce the structural distortions. Bi<sub>2</sub>O<sub>3</sub>-TiO<sub>2</sub> heterostructures can be reduced to form Bi<sup>2+</sup> and Ti<sup>3+</sup> species. The interaction of CO<sub>2</sub> with this electron-rich, reduced system can produce CO directly, reoxidising the heterostructure or form an activated carboxyl species (CO<sub>2</sub><sup>-</sup>) through electron transfer from the heterostructure to CO<sub>2</sub>. These results highlight that a semiconducting metal oxide modified with suitable metal oxide nanoclusters can activate CO<sub>2</sub>, thus overcoming the difficulties associated with the difficult first step in CO<sub>2</sub> conversion.

Sign in / Sign up

Export Citation Format

Share Document