Diastereoselective double ring closing metathesis reactions as an approach to symmetrical bicyclodienes

2000 ◽  
Vol 78 (6) ◽  
pp. 868-883 ◽  
Author(s):  
Mark Lautens ◽  
Gregory Hughes ◽  
Valentin Zunic
Keyword(s):  
Ring Closing Metathesis ◽  
Double Ring ◽  
New Class ◽  
Wide Range ◽  
Metathesis Reactions ◽  
Bicyclic Dienes

A new class of bicyclic dienes which contain a σ plane of symmetry are efficiently prepared in a diastereoselective fashion using ring closing metathesis reactions. These molecules have potential as starting materials for a wide range of organic targets.Key words: metathesis, catalysis, stereoselective, decalin, desymmetrization.

Stereoselective Double Ring Closing Metathesis Reactions in the Synthesis of Spirocyclic Compounds

Synlett ◽  
2001 ◽  
Vol 2001 (03) ◽  
pp. 0357-0360 ◽  
Author(s):  
Debra J. Wallace ◽  
Paul G. Bulger ◽  
Derek J. Kennedy ◽  
Michael S. Ashwood ◽  
Ian F. Cottrell ◽  
...  
Keyword(s):  
Ring Closing Metathesis ◽  
Double Ring ◽  
Metathesis Reactions ◽  
Spirocyclic Compounds

ChemInform Abstract: Stereoselective Double Ring Closing Metathesis Reactions in the Synthesis of Spirocyclic Compounds.

ChemInform ◽  
2010 ◽  
Vol 32 (28) ◽  
pp. no-no
Author(s):  
Debra J. Wallace ◽  
Paul G. Bulger ◽  
Derek J. Kennedy ◽  
Michael S. Ashwood ◽  
Ian F. Cottrell ◽  
...  
Keyword(s):  
Ring Closing Metathesis ◽  
Double Ring ◽  
Metathesis Reactions ◽  
Spirocyclic Compounds

Stereoselective double ring closing metathesis reactions in the synthesis of spirocyclic compounds

2000 ◽  
Vol 41 (12) ◽  
pp. 2027-2029 ◽  
Author(s):  
Debra J Wallace ◽  
Cameron J Cowden ◽  
Derek J Kennedy ◽  
Michael S Ashwood ◽  
Ian F Cottrell ◽  
...  
Keyword(s):  
Ring Closing Metathesis ◽  
Double Ring ◽  
Metathesis Reactions ◽  
Spirocyclic Compounds

ChemInform Abstract: Stereoselective Double Ring Closing Metathesis Reactions in the Synthesis of Spirocyclic Compounds.

ChemInform ◽  
2010 ◽  
Vol 31 (25) ◽  
pp. no-no
Author(s):  
Debra J. Wallace ◽  
Cameron J. Cowden ◽  
Derek J. Kennedy ◽  
Michael S. Ashwood ◽  
Ian F. Cottrell ◽  
...  
Keyword(s):  
Ring Closing Metathesis ◽  
Double Ring ◽  
Metathesis Reactions ◽  
Spirocyclic Compounds

Double Ring-Closing Approach for the Synthesis of 2,3,6,7-Substituted Anthracene Derivatives

2020 ◽  
Author(s):  
Birgit Meindl ◽  
Katharina Pfennigbauer ◽  
Berthold Stöger ◽  
Martin Heeney ◽  
Florian Glöcklhofer
Keyword(s):  
Wittig Reaction ◽  
Condensation Reaction ◽  
Synthetic Methods ◽  
Anthracene Derivative ◽  
Double Ring ◽  
Mild Conditions ◽  
Wide Range ◽  
Anthracene Derivatives

Anthracene derivatives have been used for a wide range of applications and many different synthetic methods for their preparation have been developed. However, despite continued synthetic efforts, introducing substituents in some positions has remained difficult. Here we present a method for the synthesis of 2,3,6,7-substituted anthracene derivatives, one of the most challenging anthracene substitution patterns to obtain. The method is exemplified by the preparation of 2,3,6,7-anthracenetetracarbonitrile and employs a newly developed, stable protected 1,2,4,5-benzenetetracarbaldehyde as the precursor. The precursor can be obtained in two scalable synthetic steps from 2,5-dibromoterephthalaldehyde and is converted into the anthracene derivative by a double intermolecular Wittig reaction under very mild conditions followed by a deprotection and intramolecular double ring-closing condensation reaction. Further modification of the precursor is expected to enable the introduction of additional substituents in other positions and may even enable the synthesis of fully substituted anthracene derivatives by the presented approach.<br>

Nickel-Catalyzed Inter- and Intramolecular Carbon-Sulfur Bond Metathesis by Reversible Arylation

2019 ◽  
Author(s):  
Tristan Delcaillau ◽  
Alessandro Bismuto ◽  
Zhong Lian ◽  
Bill Morandi
Keyword(s):  
Good Yield ◽  
Functional Group ◽  
Product Formation ◽  
Single Bond ◽  
Ring Closing Metathesis ◽  
Catalytic Systems ◽  
Metathesis Reactions ◽  
New Applications ◽  
Further Development ◽  
Sulfur Bond

A nickel-catalyzed carbon-sulfur bond metathesis has been developed to access high-value thioethers. 1,2-bis(dicyclohexylphosphino)ethane (dcype) is essential to promote this highly functional group tolerant reaction. Further, synthetically challenging macrocycles could be obtained in good yield in an unusual example of ring-closing metathesis which does not involve alkene bonds. In-depth organometallic studies support a reversible Ni(0)-Ni(II) pathway to product formation. Overall, this work does not only disclose a more sustainable and more functional group tolerant alternative to previous catalytic systems based on Pd, but also presents new applications and mechanistic information which are highly relevant to the further development and application of unusual single bond metathesis reactions.

scholarly journals Applications of Coupled Fixed Points for Multivalued Maps in the Equilibrium in Duopoly Markets and in Aquatic Ecosystems

Axioms ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 44
Author(s):  
Gana Gecheva ◽  
Miroslav Hristov ◽  
Diana Nedelcheva ◽  
Margarita Ruseva ◽  
Boyan Zlatanov
Keyword(s):  
Fixed Points ◽  
Aquatic Ecosystems ◽  
Market Equilibrium ◽  
Multivalued Maps ◽  
New Class ◽  
Wide Range ◽  
Coupled Fixed Points ◽  
Ordered Pairs ◽  
Duopoly Markets

We have obtained a new class of ordered pairs of multivalued maps that have pairs of coupled fixed points. We illustrate the main result with two examples that cover a wide range of models. We apply the main result in models in duopoly markets to get a market equilibrium and in aquatic ecosystems, also to get an equilibrium.

scholarly journals Recent Advances in Fabrication of Non-Isocyanate Polyurethane-Based Composite Materials

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3497
Author(s):  
Piotr Stachak ◽  
Izabela Łukaszewska ◽  
Edyta Hebda ◽  
Krzysztof Pielichowski
Keyword(s):  
Raw Materials ◽  
Synthesis Method ◽  
Polymeric Materials ◽  
Original Research ◽  
Significant Group ◽  
Oh Groups ◽  
New Class ◽  
Hazardous Chemical ◽  
Wide Range

Polyurethanes (PUs) are a significant group of polymeric materials that, due to their outstanding mechanical, chemical, and physical properties, are used in a wide range of applications. Conventionally, PUs are obtained in polyaddition reactions between diisocyanates and polyols. Due to the toxicity of isocyanate raw materials and their synthesis method utilizing phosgene, new cleaner synthetic routes for polyurethanes without using isocyanates have attracted increasing attention in recent years. Among different attempts to replace the conventional process, polyaddition of cyclic carbonates (CCs) and polyfunctional amines seems to be the most promising way to obtain non-isocyanate polyurethanes (NIPUs) or, more precisely, polyhydroxyurethanes (PHUs), while primary and secondary –OH groups are being formed alongside urethane linkages. Such an approach eliminates hazardous chemical compounds from the synthesis and leads to the fabrication of polymeric materials with unique and tunable properties. The main advantages include better chemical, mechanical, and thermal resistance, and the process itself is invulnerable to moisture, which is an essential technological feature. NIPUs can be modified via copolymerization or used as matrices to fabricate polymer composites with different additives, similar to their conventional counterparts. Hence, non-isocyanate polyurethanes are a new class of environmentally friendly polymeric materials. Many papers on the matter above have been published, including both original research and extensive reviews. However, they do not provide collected information on NIPU composites fabrication and processing. Hence, this review describes the latest progress in non-isocyanate polyurethane synthesis, modification, and finally processing. While focusing primarily on the carbonate/amine route, methods of obtaining NIPU are described, and their properties are presented. Ways of incorporating various compounds into NIPU matrices are characterized by the role of PHU materials in copolymeric materials or as an additive. Finally, diverse processing methods of non-isocyanate polyurethanes are presented, including electrospinning or 3D printing.

scholarly journals The atlas of RNase H antisense oligonucleotide distribution and activity in the CNS of rodents and non-human primates following central administration

2020 ◽  
Author(s):  
Paymaan Jafar-nejad ◽  
Berit Powers ◽  
Armand Soriano ◽  
Hien Zhao ◽  
Daniel A Norris ◽  
...  
Keyword(s):  
Motor Neurons ◽  
Muscular Atrophy ◽  
Neurological Diseases ◽  
Cell Types ◽  
Rnase H ◽  
Central Administration ◽  
Spinal Motor Neurons ◽  
New Class ◽  
Wide Range ◽  
Therapeutic Development

Abstract Antisense oligonucleotides (ASOs) have emerged as a new class of drugs to treat a wide range of diseases, including neurological indications. Spinraza, an ASO that modulates splicing of SMN2 RNA, has shown profound disease modifying effects in Spinal Muscular Atrophy (SMA) patients, energizing efforts to develop ASOs for other neurological diseases. While SMA specifically affects spinal motor neurons, other neurological diseases affect different central nervous system (CNS) regions, neuronal and non-neuronal cells. Therefore, it is important to characterize ASO distribution and activity in all major CNS structures and cell types to have a better understanding of which neurological diseases are amenable to ASO therapy. Here we present for the first time the atlas of ASO distribution and activity in the CNS of mice, rats, and non-human primates (NHP), species commonly used in preclinical therapeutic development. Following central administration of an ASO to rodents, we observe widespread distribution and target RNA reduction throughout the CNS in neurons, oligodendrocytes, astrocytes and microglia. This is also the case in NHP, despite a larger CNS volume and more complex neuroarchitecture. Our results demonstrate that ASO drugs are well suited for treating a wide range of neurological diseases for which no effective treatments are available.

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