scholarly journals Enantioselective Synthesis of Cyclic Nitrones and Oxime Ethers by Chemoselective Allylic Alkylation of Oximes

2020 ◽  
Author(s):  
Tobias Sandmeier ◽  
Erick Carreira
Keyword(s):  
Kinetic Resolution ◽  
Cycloaddition Reaction ◽  
Marine Natural Product ◽  
Allylic Alcohols ◽  
Allylic Alkylation ◽  
Reaction Conditions ◽  
Cyclic Nitrones ◽  
First Time ◽  
Reaction Cascades ◽  
Isomeric Mixtures

The enantio- and chemoselective iridium-catalyzed <i>N</i>- and<i> O</i>-allylation of oximes is described for the first time. Kinetic resolution in an intramolecular setting provides access to cyclic nitrones, oxime ethers and enantioenriched aliphatic allylic alcohols. Salient features of this transformation are its ability to employ <i>E</i>/<i>Z</i>-isomeric mixtures of oxime starting materials convergently, high functional group tolerance, and divergent <i>N</i>- or <i>O</i>-allylation by choice of the reaction conditions. The implementation of <i>N</i>-allylation/1,3-dipolar cycloaddition reaction cascades furnish tricyclic isoxazolidines in highly enantio- and diastereoselective fashion. Expansion of this approach to the selective allylation of hydrazones allows enantioselective preparation of azomethine imines. The synthetic utility of the approach is demonstrated by the efficient, formal syntheses of glycoprotein GP IIb‐IIIa receptor antagonist (–)-roxifiban and marine natural product (+)-halichlorine.

scholarly journals Enantioselective Synthesis of Cyclic Nitrones and Oxime Ethers by Chemoselective Allylic Alkylation of Oximes

2020 ◽  
Author(s):  
Tobias Sandmeier ◽  
Erick Carreira
Keyword(s):  
Kinetic Resolution ◽  
Cycloaddition Reaction ◽  
Marine Natural Product ◽  
Allylic Alcohols ◽  
Allylic Alkylation ◽  
Reaction Conditions ◽  
Cyclic Nitrones ◽  
First Time ◽  
Reaction Cascades ◽  
Isomeric Mixtures

The enantio- and chemoselective iridium-catalyzed <i>N</i>- and<i> O</i>-allylation of oximes is described for the first time. Kinetic resolution in an intramolecular setting provides access to cyclic nitrones, oxime ethers and enantioenriched aliphatic allylic alcohols. Salient features of this transformation are its ability to employ <i>E</i>/<i>Z</i>-isomeric mixtures of oxime starting materials convergently, high functional group tolerance, and divergent <i>N</i>- or <i>O</i>-allylation by choice of the reaction conditions. The implementation of <i>N</i>-allylation/1,3-dipolar cycloaddition reaction cascades furnish tricyclic isoxazolidines in highly enantio- and diastereoselective fashion. Expansion of this approach to the selective allylation of hydrazones allows enantioselective preparation of azomethine imines. The synthetic utility of the approach is demonstrated by the efficient, formal syntheses of glycoprotein GP IIb‐IIIa receptor antagonist (–)-roxifiban and marine natural product (+)-halichlorine.

scholarly journals Iridium-Catalyzed Asymmetric α-Allylic Alkylation of Amides using Vinyl Azide as Amide Enolate Surrogate

2020 ◽  
Author(s):  
Aditya Chakrabarty ◽  
Santanu Mukherjee
Keyword(s):  
Electronic Properties ◽  
Reaction Pathways ◽  
Allylic Alcohols ◽  
Allylic Alkylation ◽  
Atom Economy ◽  
Asymmetric Allylic Alkylation ◽  
Vinyl Azides ◽  
Alkylation Reactions ◽  
First Time

Among the unstabilized enolates used as nucleophile in iridium-catalyzed asymmetric allylic alkylation reactions, amide enolates are least explored. Vinyl azides are now employed as amide enolate surrogate for the first time in Ir-catalyzed asymmetric allylic alkylation with branched allylic alcohols as the allylic electrophile. Competing reaction pathways are suppressed through systematic tuning of steric and electronic properties of vinyl azide to effect α-allylic alkylation of secondary acetamides with high atom-economy, exclusive branched selectivity and moderate to excellent enantioselectivity.<br>

scholarly journals Iridium-Catalyzed Asymmetric α-Allylic Alkylation of Amides using Vinyl Azide as Amide Enolate Surrogate

2020 ◽  
Author(s):  
Aditya Chakrabarty ◽  
Santanu Mukherjee
Keyword(s):  
Electronic Properties ◽  
Reaction Pathways ◽  
Allylic Alcohols ◽  
Allylic Alkylation ◽  
Atom Economy ◽  
Asymmetric Allylic Alkylation ◽  
Vinyl Azides ◽  
Alkylation Reactions ◽  
First Time

Among the unstabilized enolates used as nucleophile in iridium-catalyzed asymmetric allylic alkylation reactions, amide enolates are least explored. Vinyl azides are now employed as amide enolate surrogate for the first time in Ir-catalyzed asymmetric allylic alkylation with branched allylic alcohols as the allylic electrophile. Competing reaction pathways are suppressed through systematic tuning of steric and electronic properties of vinyl azide to effect α-allylic alkylation of secondary acetamides with high atom-economy, exclusive branched selectivity and moderate to excellent enantioselectivity.<br>

scholarly journals A Sustainable Improvement of ω-Bromoalkylphosphonates Synthesis to Access Novel KuQuinones

Organics ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 107-117
Author(s):  
Mattia Forchetta ◽  
Valeria Conte ◽  
Giulia Fiorani ◽  
Pierluca Galloni ◽  
Federica Sabuzi
Keyword(s):  
Metal Oxides ◽  
Phosphonic Acid ◽  
Organic Molecules ◽  
Building Blocks ◽  
Reaction Conditions ◽  
Phosphonic Acids ◽  
Sustainable Improvement ◽  
Phosphonate Esters ◽  
First Time ◽  
Complex Organic

Owing to the attractiveness of organic phosphonic acids and esters in the pharmacological field and in the functionalization of conductive metal-oxides, the research of effective synthetic protocols is pivotal. Among the others, ω-bromoalkylphosphonates are gaining particular attention because they are useful building blocks for the tailored functionalization of complex organic molecules. Hence, in this work, the optimization of Michaelis–Arbuzov reaction conditions for ω-bromoalkylphosphonates has been performed, to improve process sustainability while maintaining good yields. Synthesized ω-bromoalkylphosphonates have been successfully adopted for the synthesis of new KuQuinone phosphonate esters and, by hydrolysis, phosphonic acid KuQuinone derivatives have been obtained for the first time. Considering the high affinity with metal-oxides, KuQuinones bearing phosphonic acid terminal groups are promising candidates for biomedical and photo(electro)chemical applications.

Sulfonyl Radical Triggered Selective Iodosulfonylation and Bicycli-zations of 1,6-Dienes

2021 ◽  
Author(s):  
Shi-Ping Wu ◽  
Dong-Kai Wang ◽  
Qing-Qing Kang ◽  
Guo-Ping Ge ◽  
Hongxing Zheng ◽  
...  
Keyword(s):  
Functional Group ◽  
High Selectivity ◽  
Reaction Conditions ◽  
First Time

A novel sulfonyl radical triggered selective iodosulfonylation and bicyclizations of 1,6-dienes has been described for the first time. High selectivity and efficiency, mild reaction conditions, excellent functional group compatibility, and...

Regio- and Enantioselective Rhodium-Catalyzed Allylic Alkylation of Racemic Allylic Alcohols with 1,3-Diketones

2018 ◽  
Vol 140 (24) ◽  
pp. 7737-7742 ◽  
Author(s):  
Sheng-Biao Tang ◽  
Xiao Zhang ◽  
Hang-Fei Tu ◽  
Shu-Li You
Keyword(s):  
Allylic Alcohols ◽  
Allylic Alkylation

scholarly journals Chemoenzymatic Dynamic Kinetic Resolution of Allylic Alcohols: A Highly Enantioselective Route to Acyloin Acetates.

ChemInform ◽  
2007 ◽  
Vol 38 (52) ◽  
Author(s):  
Krisztian Bogar ◽  
Pilar Hoyos Vidal ◽  
Andres R. Alcantara Leon ◽  
Jan-E. Baeckvall
Keyword(s):  
Kinetic Resolution ◽  
Allylic Alcohols ◽  
Dynamic Kinetic Resolution

scholarly journals New opportunities in the stereoselective dearomatization of indoles

2016 ◽  
Vol 88 (3) ◽  
pp. 207-214 ◽  
Author(s):  
Elisabetta Manoni ◽  
Assunta De Nisi ◽  
Marco Bandini
Keyword(s):  
Acid Catalysis ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Reaction Conditions ◽  
Brönsted Acid ◽  
High Yields ◽  
First Time ◽  
Tailored Design ◽  
Bronsted Acid Catalysis

AbstractThe regio- and stereoselective dearomatization of indoles is realized for the first time by combining readily available indolyl precursors and electron-rich allenes, namely allenamides and aryloxyallenes. Inter- as well as intramolecular condensations were realized under gold and Brønsted acid catalysis providing a range of densely functionalized indoline and indolenine cores in high yields and excellent stereochemical outcome. Chemodivergent reaction profiles (Micheal-type addition vs. [2+2]-cycloaddition) were realized by a tailored design of both reaction conditions and functionalization of the reaction partners.

scholarly journals Visible Light-Enabled Paternò-Büchi Reaction via Triplet Energy Transfer for the Synthesis of Oxetanes

2020 ◽  
Author(s):  
Katie Rykaczewski ◽  
Corinna Schindler
Keyword(s):  
Energy Transfer ◽  
Visible Light ◽  
Uv Light ◽  
Cycloaddition Reaction ◽  
High Energy ◽  
Triplet Energy ◽  
Reaction Conditions ◽  
Triplet Energy Transfer

<div> <p>One of the most efficient ways to synthesize oxetanes is the light-enabled [2+2] cycloaddition reaction of carbonyls and alkenes, referred to as the Paternò-Büchi reaction. The reaction conditions for this transformation typically require the use of high energy UV light to excite the carbonyl, limiting the applications, safety, and scalability. We herein report the development of a visible light-mediated Paternò-Büchi reaction protocol that relies on triplet energy transfer from an iridium-based photocatalyst to the carbonyl substrates. This mode of activation is demonstrated for a variety of aryl glyoxylates and negates the need for both, visible light-absorbing carbonyl starting materials or UV light to enable access to a variety of functionalized oxetanes in up to 99% yield.</p> </div> <br>

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