scholarly journals Consecutive Ring-Expansion Reactions for the Iterative Assembly of Medium-Sized Rings and Macrocycles

Synlett ◽  
2019 ◽  
Vol 31 (02) ◽  
pp. 133-146 ◽  
Author(s):  
Thomas C. Stephens ◽  
William P. Unsworth
Keyword(s):  
Ring Expansion ◽  
Pericyclic Reactions ◽  
Cyclization Reactions ◽  
Design And Synthesis ◽  
Current State ◽  
Radical Cascade ◽  
Aminyl Radical ◽  
Fragmentation Reactions ◽  
Iterative Synthesis ◽  
Scientific Fields

Macrocycles and medium-sized rings have important applications in several scientific fields but can be challenging to make using traditional end-to-end cyclization reactions. Ring-expansion methods represent a useful alternative and offer numerous practical benefits. In this Account, we discuss the current state of the art of ring-expansion strategies that have been applied consecutively. Such methods have the power to expedite the design and synthesis of functionalized macro­cycles via the selective, iterative insertion of smaller fragments into ring-enlarged products.1 Introduction2 Insertion Reactions2.1 Transamidation/Transpeptidation2.2 Transesterification2.3 Transthioesterification2.4 Aminyl Radical Cascade2.5 Iterative Synthesis of Lactones2.6 Successive Ring Expansion of β-Ketoesters and Lactams3 Pericyclic Reactions3.1 Sulfur-Mediated Rearrangements3.2 Nitrogen-Mediated Rearrangements4 Fragmentation Reactions5 Conclusions and Future Outlook

Short Review and opinion: New matter properties and applications based on Hybrids Graphene based Metamaterials

2020 ◽  
Vol 04 ◽  
Author(s):  
A. Guillermo Bracamonte
Keyword(s):  
Short Review ◽  
New Materials ◽  
Design And Synthesis ◽  
Chemical Structures ◽  
Current State ◽  
Potential Applications ◽  
Fundamental Research ◽  
Miniaturized Instrumentation ◽  
And Control ◽  
Conductive Properties

: Graphene as Organic material showed special attention due to their electronic and conductive properties. Moreover, its highly conjugated chemical structures and relative easy modification permitted varied design and control of targeted properties and applications. In addition, this Nanomaterial accompanied with pseudo Electromagnetic fields permitted photonics, electronics and Quantum interactions with their surrounding that generated new materials properties. In this context, this short Review, intends to discuss many of these studies related with new materials based on graphene for light and electronic interactions, conductions, and new modes of non-classical light generation. It should be highlighted that these new materials and metamaterials are currently in progress. For this reason it was showed and discussed some representative examples from Fundamental Research with Potential Applications as well as for their incorporations to real Advanced devices and miniaturized instrumentation. In this way, it was proposed this Special issue entitled “Design and synthesis of Hybrids Graphene based Metamaterials”, in order to open and share the knowledge of the Current State of the Art in this Multidisciplinary field.

scholarly journals Recent Developments in Polyene Cyclizations and Their Applications in Natural Product Synthesis

Synthesis ◽  
2018 ◽  
Vol 51 (01) ◽  
pp. 67-82 ◽  
Author(s):  
Anthony Barrett ◽  
Tsz-Kan Ma ◽  
Thomas Mies
Keyword(s):  
Transition Metal ◽  
Natural Product ◽  
Lewis Acid ◽  
Multiple Bond ◽  
Natural Product Synthesis ◽  
Cyclization Reactions ◽  
Cascade Cyclizations ◽  
Highly Efficient ◽  
Recent Developments ◽  
Radical Cascade

Cascade polyene cyclization reactions are highly efficient and elegant bioinspired transformations that involve simultaneous multiple bond constructions to rapidly generate complex polycyclic molecules. This review summarizes the most prominent work on a variety of cationic and radical cascade cyclizations and their applications in natural product synthesis published between 2014 and 2018.1 Introduction2 Cationic Polyene Cyclizations2.1 Lewis Acid Mediated Polyene Cyclizations2.2 Brønsted Acid Mediated Polyene Cyclizations2.3 Halogen Electrophile Initiated Polyene Cyclizations2.4 Sulfur Electrophile Initiated Polyene Cyclizations2.5 Transition-Metal-Mediated Cationic Polyene Cyclizations3 Radical Polyene Cyclizations3.1 Transition-Metal-Mediated Radical Polyene Cyclizations3.2 Photocatalyst-Mediated Polyene Cyclizations4 Origin of Stereocontrol in Polyene Cyclizations5 Conclusion

scholarly journals The postdigital turn: Philosophy, education, research

2021 ◽  
pp. 147821032110627
Author(s):  
Petar Jandrić ◽  
Jeremy Knox
Keyword(s):  
Education Research ◽  
Educational Research ◽  
State Of The Art ◽  
The Third ◽  
Current State ◽  
Digital Physics ◽  
Future Work ◽  
Scientific Fields

This article develops a post-determinist and a post-instrumentalist understanding of education and educational research through the lens of postdigital theory. We begin with historicizing current postdigital research by showing its intellectual ancestry and recognizing its rapidly changing nature. We move on to current state of the art, which we present in three wide themes. The first theme is the great convergence of various lower-level techno-scientific convergences, such as analogue–digital, physics–biology, and biology–information, which results in new epistemologies, ontologies and practices. The second theme is some consequences of the great convergence for education and pedagogy, which result in new postdigital ecopedagogies. The third theme is postdigital research, which is reconfigured by the great convergence towards a closer collaboration between traditional scientific fields and disciplines. We briefly outline four such reconfigurations (multidisciplinary, interdisciplinarity, transdisciplinarity, and antidisciplinarity) and their implications. The article concludes with a brief list of directions for future work in the field.

Cascade Radical Cyclization-Fragmentation-Transannular-Ring Expansion Reactions Involving Oximes. A New Approach to Synthesis of Angular Triquinanes

1995 ◽  
Vol 48 (2) ◽  
pp. 381 ◽  
Author(s):  
GJ Hollingworth ◽  
G Pattenden ◽  
DJ Schulz
Keyword(s):  
Main Product ◽  
Ring Expansion ◽  
Radical Cyclization ◽  
One Pot ◽  
New Approach ◽  
Vinyl Bromide ◽  
Radical Intermediates ◽  
Double Ring ◽  
Radical Fragmentation ◽  
Aminyl Radical

Treatment of the acetylene-substituted cyclobutanone oxime ether (13) with (Me3Si)3SiH leads, in one pot, to the 5,6-bicyclic enone oxime (14) in 70% yield. It is suggested that the formation of (14) from (13) proceeds by way of a novel double ring expansion-transannulation process involving aminyl radical intermediates (see Scheme 3, below). By contrast, treatment of the cyclobutanone (3a) with Bu3SnH instead leads only to the product (11) of hydrostannylation of the acetylene unit in (3a). Neither (3a) nor (13) produced any of the expected bicyclo[3.3.0]octane products, viz. (5a) and (15), following treatment with silanes or stannanes. When a solution of the vinyl bromide-substituted cyclobutanone oxime (42) was irradiated with a sunlamp in the presence of (Me3Si)3SiH, the main product isolated was the triquinane (45) (38%) resulting from a cascade radical 6-exo-trig cyclization, aminyl radical fragmentation, 5-exo-trig radical transannulation, 5-exo-trig cyclization sequence.

ChemInform Abstract: Design and Synthesis of Polycyclic Imidazole-Containing N-Heterocycles Based on C-H Activation/Cyclization Reactions.

ChemInform ◽  
2013 ◽  
Vol 44 (12) ◽  
pp. no-no
Author(s):  
Viktor O. Iaroshenko ◽  
Dmytro Ostrovskyi ◽  
Mariia Miliutina ◽  
Aneela Maalik ◽  
Alexander Villinger ◽  
...  
Keyword(s):  
Cyclization Reactions ◽  
Design And Synthesis

Short Review and Opinion: New Matter Properties and Applications Based on Hybrids Graphene Based Metamaterials

2021 ◽  
Vol 14 ◽  
Author(s):  
A. Guillermo Bracamonte
Keyword(s):  
Short Review ◽  
New Materials ◽  
Design And Synthesis ◽  
Chemical Structures ◽  
Current State ◽  
Potential Applications ◽  
Fundamental Research ◽  
Miniaturized Instrumentation ◽  
And Control ◽  
Conductive Properties

: Graphene as Organic material showed special attention due to their electronic and conductive properties. Moreover, its highly conjugated chemical structures and relative easy modification permitted varied design and control of targeted properties and applications. In addition, this Nanomaterial accompanied with pseudo Electromagnetic fields permitted photonics, electronics and Quantum interactions with their surrounding that generated new materials properties. In this context, this short Review, intends to discuss many of these studies related with new materials based on graphene for light and electronic interactions, conductions, and new modes of non-classical light generation. It should be highlighted that these new materials and metamaterials are currently in progress. For this reason it was showed and discussed some representative examples from Fundamental Research with Potential Applications as well as for their incorporations to real Advanced devices and miniaturized instrumentation. In this way, it was proposed this Special issue entitled “Design and synthesis of Hybrids Graphene based Metamaterials”, in order to open and share the knowledge of the Current State of the Art in this Multidisciplinary field.

Mechanismen der elektronenstoßinduzierten Methanoleliminierung aus ortho- und para-substituierten Benzoesäuremethylestern / Mechanisms of Electron Impact Induced Elimination of Methanol from ortho- and para-Substituted Benzoic Acid Methyl Ester

1976 ◽  
Vol 31 (6) ◽  
pp. 870-875 ◽  
Author(s):  
Rupert Herrmann ◽  
Helmut Schwarz
Keyword(s):  
Mass Spectrometry ◽  
Methyl Ester ◽  
Benzoic Acid ◽  
Electron Impact ◽  
Acid Methyl Ester ◽  
Ring Expansion ◽  
Acid Methyl ◽  
Π Complex ◽  
Fragmentation Reactions ◽  
Ring Expansion Reaction

Using deuterium labelled compounds the mechanisms of methyl as well as methanol elimination from the title compounds have been established. It can be shown that in the case of 4-methoxy-methyl benzoic acid methyl ester the unusual methanol elimination from the [M-methyl]+ ion probably proceeds via the formation of a π-complex and a ring expansion reaction. In addition to this novel fragmentation some ortho-effects and other fragmentation reactions useful for an analytical identification of the ortho/para-isomers by means of mass spectrometry are discussed.

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