scholarly journals DDQ-Promoted Mild and Efficient Metal-Free Oxidative α-Cyanation of N-Acyl/Sulfonyl 1,2,3,4-Tetrahydroisoquinolines

Molecules ◽  
2018 ◽  
Vol 23 (12) ◽  
pp. 3223 ◽  
Author(s):  
Hong Kim ◽  
Heesun Yu ◽  
Hyoungsu Kim ◽  
Seok-Ho Kim ◽  
Dongjoo Lee
Keyword(s):  
Total Synthesis ◽  
Ambient Temperature ◽  
Natural Product ◽  
Natural Product Synthesis ◽  
Protecting Groups ◽  
Metal Free ◽  
Wide Range ◽  
Iminium Ions ◽  
Synthetic Utility ◽  
Ddq Oxidation

A mild and highly efficient metal-free oxidative α-cyanation of N-acyl/sulfonyl 1,2,3,4-tetrahydroisoquinolines (THIQs) has been accomplished at an ambient temperature via DDQ oxidation and subsequent trapping of N-acyl/sulfonyl iminium ions with (n-Bu)3SnCN. Employing readily removable N-acyl/sulfonyl groups as protecting groups rather than N-aryl ones enables a wide range of applications in natural product synthesis. The synthetic utility of the method was illustrated using a short and efficient formal total synthesis of (±)-calycotomine in three steps.

Alkynyl Prins and Alkynyl Aza-Prins Annulations: Scope and Synthetic Applications

Synthesis ◽  
2020 ◽  
Vol 52 (14) ◽  
pp. 1991-2007 ◽  
Author(s):  
Alison J. Frontier ◽  
Shukree Abdul-Rashed ◽  
Connor Holt
Keyword(s):  
Natural Products ◽  
Small Molecules ◽  
Natural Product ◽  
Natural Product Synthesis ◽  
Pericyclic Reactions ◽  
Prins Reaction ◽  
Prins Cyclization ◽  
Synthetic Utility ◽  
Cascade Processes ◽  
Saturated Heterocycles

This review focuses on alkynyl Prins and alkynyl aza-Prins cyclization­ processes, which involve intramolecular coupling of an alkyne with either an oxocarbenium or iminium electrophile. The oxocarbenium or iminium species can be generated through condensation- or elimination-type processes, to achieve an overall bimolecular annulation that enables the synthesis of both oxygen- and nitrogen-containing­ saturated heterocycles with different ring sizes and substitution patterns. Also discussed are cascade processes in which alkynyl Prins heterocyclic adducts react to trigger subsequent pericyclic reactions, including [4+2] cycloadditions and Nazarov electrocyclizations, to rapidly construct complex small molecules. Finally, examples of the use of alkynyl Prins and alkynyl aza-Prins reactions in the synthesis of natural products are described. The review covers the literature through the end of 2019.1 Introduction1.1 Alkyne-Carbonyl Coupling Pathways1.2 Coupling/Cyclization Cascades Using the Alkynyl Prins Reaction2 Alkynyl Prins Annulation (Oxocarbenium Electrophiles)2.1 Early Work2.2 Halide as Terminal Nucleophile2.3 Oxygen as Terminal Nucleophile2.4 Arene as Terminal Nucleophile (Intermolecular)2.5 Arene Terminal Nucleophile (Intramolecular)2.6 Cyclizations Terminated by Elimination3 Synthetic Utility of Alkynyl Prins Annulation3.1 Alkynyl Prins-Mediated Synthesis of Dienes for a [4+2] Cyclo­- addition­-Oxidation Sequence3.2 Alkynyl Prins Cyclization Adducts as Nazarov Cyclization Precursors3.3 Alkynyl Prins Cyclization in Natural Product Synthesis4 Alkynyl Aza-Prins Annulation4.1 Iminium Electrophiles4.2 Activated Iminium Electrophiles5 Alkynyl Aza-Prins Cyclizations in Natural Product Synthesis6 Summary and Outlook

Ir-Catalyzed reactions in natural product synthesis

2018 ◽  
Vol 5 (1) ◽  
pp. 132-150 ◽  
Author(s):  
Pengquan Chen ◽  
Yuecheng Wu ◽  
Shifa Zhu ◽  
Huanfeng Jiang ◽  
Zhiqiang Ma
Keyword(s):  
Natural Products ◽  
Total Synthesis ◽  
Natural Product ◽  
Natural Product Synthesis ◽  
Catalyzed Reactions

This review highlights the recent applications of Ir-catalyzed reactions in the total synthesis of natural products.

A transition metal-free approach to a regioselective total synthesis of the natural product derivative 6-methylellipticine, a potent anticancer agent

2019 ◽  
Vol 60 (51) ◽  
pp. 151309 ◽  
Author(s):  
Song-Bo Lin ◽  
Wan-Wan Wang ◽  
Jin-Peng Meng ◽  
Xi-Wang Li ◽  
Jun Wu ◽  
...  
Keyword(s):  
Transition Metal ◽  
Total Synthesis ◽  
Natural Product ◽  
Anticancer Agent ◽  
Metal Free

Convergent Total Synthesis of (–)-Principinol D, a Rearranged Kaurane Diterpenoid

2019 ◽  
Author(s):  
Aneta Turlik ◽  
Yifeng Chen ◽  
Anthony Scruse ◽  
Timothy Newhouse
Keyword(s):  
Total Synthesis ◽  
Natural Product ◽  
Late Stage ◽  
Membered Ring ◽  
Entry Point ◽  
Ketone Reduction ◽  
Wide Range ◽  
Coupling Approach

<div> <p>The total synthesis of principinol D, a rearranged kaurane diterpenoid, is reported. This grayanane natural product was constructed via a convergent fragment coupling approach, wherein the central 7-membered ring was synthesized at a late stage. The <a>bicyclo</a>[3.2.1]octane fragment is accessed by a Ni-catalyzed α-vinylation reaction, followed by a diastereoselective SmI<sub>2</sub>-mediated ketone reduction. The convergent strategy reported herein may be an entry point to a wide range of kaurane diterpenoids. </p> </div>

Synthesis of α-exo-Methylene-γ-butyrolactone: Recent Developments and Applications in Natural Product Synthesis

Synthesis ◽  
2021 ◽  
Author(s):  
Weilong Liu ◽  
Nicolas Winssinger
Keyword(s):  
Natural Products ◽  
Biological Activity ◽  
Total Synthesis ◽  
Natural Product ◽  
Natural Product Synthesis ◽  
Vast Array ◽  
The Past ◽  
New Approaches ◽  
Recent Developments

The α-exo-methylene-γ-butyrolactone moiety is present in a vast array of structurally diverse natural products and is often central to their biological activity. In this review, we summarize new approaches to α-exo-methylene-γ-butyrolactones developed over the past decade as well as their applications in total synthesis.

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