scholarly journals Catalytic, contra-Thermodynamic Alkene Isomerization

2021 ◽  
Author(s):  
Gino Occhialini ◽  
Vignesh Palani ◽  
Alison Wendlandt
Keyword(s):  
Natural Product ◽  
Catalyst System ◽  
Natural Product Synthesis ◽  
Mechanistic Studies ◽  
Double Bonds ◽  
Positional Isomerization ◽  
Alkene Isomerization ◽  
Terminal Alkene ◽  
Homolytic Substitution ◽  
Powerful Strategy

The positional isomerization of C–C double bonds is a powerful strategy for the interconversion of alkene regioisomers. However, existing methods provide access to thermodynamically more stable isomers from less stable starting materials. Here we report the discovery of a dual catalyst system that promotes contra-thermodynamic positional alkene isomerization under photochemical irradiation, providing access to terminal alkene isomers directly from conjugated, internal alkene starting materials. The utility of the method is demonstrated in the deconjugation of diverse electron rich/poor alkenes and through strategic application to natural product synthesis. Mechanistic studies are consistent with a regiospecific bimolecular homolytic substitution (SH2') mechanism proceeding through an allyl-cobaloxime intermediate.

scholarly journals The Synthesis of Conjugated Bis-Aryl Vinyl Substrates and Their Photoelectrocyclization Reactions towards Phenanthrene Derivatives

Synthesis ◽  
2021 ◽  
Author(s):  
Jon D. Rainier ◽  
Xuchen Zhao
Keyword(s):  
Natural Product ◽  
Natural Product Synthesis ◽  
Mechanistic Studies ◽  
Efficient Strategy

AbstractThe photoelectrocyclization of conjugated vinyl biaryls has proven to be a valuable and efficient strategy for generating phenanthrene derivatives. Contained in this review is an overview of the mechanism for the transformation and a discussion of the reaction scope with a focus on the electrocyclization itself, rearomatization, and the application of the reaction in natural product synthesis.1 Introduction2 The Synthesis of Conjugated Vinyl Biaryls3 Mechanistic Studies4 Substrate Scope5 Applications6 Conclusions

Cascades Involving anti-Carbopalladation Steps: From Our Initial Hypothesis to Natural Product Synthesis

Synlett ◽  
2019 ◽  
Vol 30 (11) ◽  
pp. 1275-1288 ◽  
Author(s):  
Theresa Schitter ◽  
Andreas Reding ◽  
Daniel B. Werz
Keyword(s):  
Total Synthesis ◽  
Natural Product ◽  
Reaction Mechanisms ◽  
Indole Alkaloid ◽  
Cascade Reactions ◽  
Natural Product Synthesis ◽  
Personal Perspective ◽  
Double Bonds ◽  
Initial Hypothesis ◽  
The Way

Our endeavors in the design, realization and application of a formal anti-carbopalladation of alkynes are summarized. Whereas numerous examples of syn-carbopalladation steps embedded in cascade reactions are known, there have been almost no examples of the corresponding anti-carbopalladation steps. From a personal perspective, this account provides insights on the original considerations and hypotheses, and their validation or invalidation by experimental and computational means. This account also aims at clarifying how different ideas have been developed and how novel reaction sequences paving the way to a plethora of different scaffolds have been designed. The reader will recognize the importance of the interplay between elucidating reaction mechanisms and developing novel methodologies. As a result, useful methods to create homo- and heterotetrasubstituted double bonds have been developed. The broad versatility of these methods has been demonstrated by a novel total synthesis of the indole alkaloid (+)-lysergol.1 Introduction2 Initial Studies3 Various Termination Steps4 Termination with Heteronucleophiles5 Natural Product Synthesis6 anti-Carbopalladations Realized by the Lautens Lab7 Conclusion and Outlook

Formation of tetrasubstituted C–C double bonds via olefin metathesis: challenges, catalysts, and applications in natural product synthesis

2018 ◽  
Vol 5 (3) ◽  
pp. 494-516 ◽  
Author(s):  
Nirmalya Mukherjee ◽  
Sebastian Planer ◽  
Karol Grela
Keyword(s):  
Transition Metal ◽  
Natural Product ◽  
Olefin Metathesis ◽  
Natural Product Synthesis ◽  
Synthetic Chemistry ◽  
Double Bonds ◽  
Bond Forming ◽  
Bond Forming Reactions ◽  
The Many

Among the many types of transition-metal-catalysed C–C bond forming reactions, olefin metathesis is without a doubt one of the most thriving fields in modern organic synthetic chemistry.

Recent applications of asymmetric organocatalytic annulation reactions in natural product synthesis

2021 ◽  
Author(s):  
Nengzhong Wang ◽  
Zugen Wu ◽  
Junjie Wang ◽  
Nisar Ullah ◽  
Yixin Lu
Keyword(s):  
Natural Products ◽  
Natural Product ◽  
Natural Product Synthesis ◽  
Natural Products Synthesis

A comprehensive and updated summary of asymmetric organocatalytic annulation reactions is presented; in particular, the applications of these annulation strategies to natural products synthesis are highlighted.

Palladium-catalyzed cascade cyclizations involving C–C and C–X bond formation: strategic applications in natural product synthesis

2021 ◽  
Author(s):  
K. R. Holman ◽  
A. M. Stanko ◽  
S. E. Reisman
Keyword(s):  
Natural Product ◽  
Bond Formation ◽  
Natural Product Synthesis ◽  
Cascade Cyclizations ◽  
Palladium Catalyzed ◽  
Multiple Rings

This tutorial review highlights the use of palladium-catalyzed cascade cyclizations in natural product synthesis, focusing on cascades that construct multiple rings and form both C–C and C–X (X = O, N) bonds in a single synthetic operation.

scholarly journals Applications of the Horner-Wadsworth-Emmons olefination in modern natural product synthesis

Synthesis ◽  
2021 ◽  
Author(s):  
Dávid Roman ◽  
Maria Sauer ◽  
Christine Beemelmanns
Keyword(s):  
Natural Products ◽  
Natural Product ◽  
Natural Product Synthesis ◽  
Reaction Conditions ◽  
Comprehensive Review ◽  
Modern Natural ◽  
Key Steps ◽  
Synthetic Approaches

Here, we have summarized more than 30 representative natural product syntheses published in 2015 to 2020 that employ one or more Horner-Wadsworth-Emmons (HWE) reactions. We comprehensively describe the applied phosphonate reagents, HWE reaction conditions and key steps of the total synthetic approaches. Our comprehensive review will support future synthetic approaches and serve as guideline to find the best HWE conditions for the most complicated natural products known

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