Stereochemical consequences of the Lewis acid catalyzed cyclocondensation of oxygenated dienes with aldehydes. A rapid and stereoselective entry to various natural products derived from propionate

1982 ◽  
Vol 104 (1) ◽  
pp. 360-362 ◽  
Author(s):  
Samuel Danishefsky ◽  
Nobuo Kato ◽  
David Askin ◽  
James F. Kerwin
Keyword(s):  
Natural Products ◽  
Lewis Acid ◽  
Acid Catalyzed

Accessing Polycyclic Terpenoids from Zerumbone via Lewis Acid Catalyzed Synthetic Strategies

Synthesis ◽  
2020 ◽  
Vol 52 (14) ◽  
pp. 2045-2064 ◽  
Author(s):  
Puthiyaparambath Sharathna ◽  
Murugan Thulasi Meenu ◽  
Kokkuvayil Vasu Radhakrishnan ◽  
Bhandara Purayil Dhanya ◽  
Greeshma Gopalan ◽  
...  
Keyword(s):  
Natural Products ◽  
Lewis Acid ◽  
Biologically Active Compounds ◽  
Biologically Active ◽  
Effective Strategy ◽  
Structural Elements ◽  
Nazarov Cyclization ◽  
Active Compounds ◽  
Acid Catalyzed

We herein disclose an effective strategy for the synthesis of [5.3.0] and [6.3.0] fused polycyclic terpenoids, which are important structural elements of natural products and biologically active compounds. The method comprises of Lewis acid catalyzed interrupted Nazarov cyclization of zerumbone derivatives such as zerumbone epoxide, triazole-appended zerumbone, zerumbal, and zerumbenone with a wide substrate scope with different indoles. Zerumbone epoxide furnished [5.3.0] and [6.3.0] fused structurally diverse sesquiterpenoids and all other zerumbone derivatives furnished the [6.3.0] fused motifs.

scholarly journals Protecting group free enantiospecific total syntheses of structurally diverse natural products of the tetrahydrocannabinoid family

2015 ◽  
Vol 51 (14) ◽  
pp. 2871-2873 ◽  
Author(s):  
Dattatraya H. Dethe ◽  
Rohan D. Erande ◽  
Samarpita Mahapatra ◽  
Saikat Das ◽  
Vijay Kumar B.
Keyword(s):  
Natural Products ◽  
Lewis Acid ◽  
Allylic Alcohol ◽  
Protecting Group ◽  
Total Syntheses ◽  
Acid Catalyzed

A simple, highly diastereoselective, Lewis acid catalyzed Friedel–Crafts coupling of a cyclic allylic alcohol with resorcinol derivatives has been developed.

scholarly journals Lewis Acid Mediated Cyclizations: Diastereoselective Synthesis of Six- to Eight-Membered Substituted Cyclic Ethers

Synthesis ◽  
2017 ◽  
Vol 49 (18) ◽  
pp. 4229-4246 ◽  
Author(s):  
Arun Ghosh ◽  
Anthony Tomaine ◽  
Kelsey Cantwell
Keyword(s):  
Natural Products ◽  
Drug Design ◽  
Lewis Acid ◽  
Medicinal Chemistry ◽  
Cyclic Ether ◽  
Cyclic Ethers ◽  
Diastereoselective Synthesis ◽  
Acid Catalyzed

Cyclic ethers are widely abundant in natural products. Cyclic ether templates are also utilized in drug design and medicinal chemistry. Although the synthetic processes for this class of compounds have been studied extensively with respect to five- and six-membered rings, medium-sized cyclic ethers are synthetically more challenging due to a variety of factors. Herein, we report our results on the Lewis acid catalyzed synthesis of medium-sized cyclic ethers in a diastereoselective manner.

scholarly journals Highly enantioselective access to cannabinoid-type tricyles by organocatalytic Diels–Alder reactions

2012 ◽  
Vol 8 ◽  
pp. 1385-1392 ◽  
Author(s):  
Stefan Bräse ◽  
Nicole Volz ◽  
Franziska Gläser ◽  
Martin Nieger
Keyword(s):  
Natural Products ◽  
Lewis Acid ◽  
Enantiomeric Excess ◽  
Diels Alder ◽  
Starting Material ◽  
Asymmetric Induction ◽  
Domino Reactions ◽  
Modular Synthesis ◽  
Acid Catalyzed ◽  
Novel Strategy

After prosperous domino reactions towards benzopyrans, the products were used as the starting material in Lewis acid catalyzed and organocatalytic Diels–Alder reactions to build up a tricyclic system. Herein, an asymmetric induction up to 96% enantiomeric excess was obtained by the use of imidazolidinone catalysts. This approach can be utilized to construct the tricyclic system in numerous natural products, in particular the scaffold of tetrahydrocannabinol (THC) being the most representative one. Compared with other published methods, condensation with a preexisting cyclohexane moiety in the precursor is needed to gain the heterogenic tricycle systems, whereas we present a novel strategy towards cannabinoid derivatives based on a flexible modular synthesis.

scholarly journals Collective synthesis of acetylenic pharmaceuticals via enantioselective Nickel/Lewis acid-catalyzed propargylic alkylation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xihao Chang ◽  
Jiayin Zhang ◽  
Lingzi Peng ◽  
Chang Guo
Keyword(s):  
Organic Chemistry ◽  
Natural Products ◽  
Functional Groups ◽  
Bioactive Compounds ◽  
Lewis Acid ◽  
Mild Condition ◽  
Substitution Reaction ◽  
Biologically Active ◽  
Acid Catalyzed ◽  
Propargylic Substitution

AbstractChiral acetylenic derivatives are found in many bioactive compounds and are versatile functional groups in organic chemistry. Here, we describe an enantioselective nickel/Lewis acid-catalyzed asymmetric propargylic substitution reaction from simple achiral materials under mild condition. The introduction of a Lewis acid cocatalyst is crucial to the efficiency of the transformation. Notably, we investigate this asymmetric propargylic substitution reaction for the development of a range of structurally diverse natural products. The power of this strategy is highlighted by the collective synthesis of seven biologically active compounds: (−)-Thiohexital, (+)-Thiopental, (+)-Pentobarbital, (−)-AMG 837, (+)-Phenoxanol, (+)-Citralis, and (−)-Citralis Nitrile.

Catalytic Carbonyl-Olefin Metathesis of Aliphatic Ketones: Iron(III) HomoDimers as Lewis Acidic Superelectrophiles

2018 ◽  
Author(s):  
Haley Albright ◽  
Paul S. Riehl ◽  
Christopher C. McAtee ◽  
Jolene P. Reid ◽  
Jacob R. Ludwig ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Olefin Metathesis ◽  
Acid Activation ◽  
Lewis Acid Catalysts ◽  
Distinct Mode ◽  
Aliphatic Ketones ◽  
Carbon Carbon Bond ◽  
Metathesis Reactions ◽  
Acid Catalyzed

<div>Catalytic carbonyl-olefin metathesis reactions have recently been developed as a powerful tool for carbon-carbon bond</div><div>formation. However, currently available synthetic protocols rely exclusively on aryl ketone substrates while the corresponding aliphatic analogs remain elusive. We herein report the development of Lewis acid-catalyzed carbonyl-olefin ring-closing metathesis reactions for aliphatic ketones. Mechanistic investigations are consistent with a distinct mode of activation relying on the in situ formation of a homobimetallic singly-bridged iron(III)-dimer as the active catalytic species. These “superelectrophiles” function as more powerful Lewis acid catalysts that form upon association of individual iron(III)-monomers. While this mode of Lewis acid activation has previously been postulated to exist, it has not yet been applied in a catalytic setting. The insights presented are expected to enable further advancement in Lewis acid catalysis by building upon the activation principle of “superelectrophiles” and broaden the current scope of catalytic carbonyl-olefin metathesis reactions.</div>

Enantioselective Syntheses of Flavonoid Diels-Alder Natural Products: A Review

2018 ◽  
Vol 15 (2) ◽  
pp. 221-229 ◽  
Author(s):  
Shah Bakhtiar Nasir ◽  
Noorsaadah Abd Rahman ◽  
Chin Fei Chee
Keyword(s):  
Natural Products ◽  
Organic Synthesis ◽  
Lewis Acid ◽  
Alder Reaction ◽  
Diels Alder ◽  
Enantioselective Synthesis ◽  
Chiral Ligand ◽  
Asymmetric Syntheses ◽  
Diels Alder Reaction ◽  
Enantioselective Syntheses

Background: The Diels-Alder reaction has been widely utilised in the syntheses of biologically important natural products over the years and continues to greatly impact modern synthetic methodology. Recent discovery of chiral organocatalysts, auxiliaries and ligands in organic synthesis has paved the way for their application in Diels-Alder chemistry with the goal to improve efficiency as well as stereochemistry. Objective: The review focuses on asymmetric syntheses of flavonoid Diels-Alder natural products that utilize chiral ligand-Lewis acid complexes through various illustrative examples. Conclusion: It is clear from the review that a significant amount of research has been done investigating various types of catalysts and chiral ligand-Lewis acid complexes for the enantioselective synthesis of flavonoid Diels-Alder natural products. The results have demonstrated improved yield and enantioselectivity. Much emphasis has been placed on the synthesis but important mechanistic work aimed at understanding the enantioselectivity has also been discussed.

Intramolecular Diels–Alder Reactions of Oxazoles, Imidazoles, and Thiazoles

Synthesis ◽  
2020 ◽  
Author(s):  
Peter Wipf ◽  
Thanh T. Nguyen
Keyword(s):  
Natural Products ◽  
Lewis Acid ◽  
Acid Catalysis ◽  
Copper Catalysts ◽  
Diels Alder ◽  
Synthetic Approach ◽  
Highly Efficient ◽  
Intramolecular Cycloadditions ◽  
Western Segment ◽  
Target Molecules

AbstractThe development of the intramolecular Diels–Alder cycloaddition­ of azole heterocycles, i.e. oxazoles (IMDAO), imidazoles (IMDAI), and thiazoles (IMDAT), has had a significant impact on the efficient preparation of heterocyclic intermediates and natural products. In particular, highly efficient and versatile IMDAO reactions have been utilized as a key step in several synthetic schemes to provide alkaloids and terpenoid target molecules. More limited studies have been performed on IMDAI and IMDAT cycloadditions. Some drawbacks, such as the occasionally­ challenging preparation of IMDA precursors, are also highlighted in this review. Perspectives are provided on how IMDAI and IMDAT­ transformations can be further expanded for target-directed syntheses.1 Introduction2 Oxazoles2.1 IMDAO Approaches to Furanosesquiterpenes and Furanosteroids2.1.1 Syntheses of Highly Oxygenated Sesquiterpenes2.1.2 Syntheses of (±)-Gnididione and (±)-Isognididione2.1.3 Synthesis of (±)-Stemoamide2.1.4 Synthesis of (±)-Paniculide A2.1.5 Syntheses of (+)- and (–)-Norsecurinine2.1.6 Synthesis of Evodone2.1.7 Syntheses of (±)-Ligularone and (±)-Petasalbine2.1.8 Syntheses of Imerubrine, Isoimerubrine, and Grandirubrine2.1.9 Syntheses of Furanosteroids2.1.10 Syntheses of Substituted Indolines and Tetrahydroquinolines2.2 IMDAO Approaches to Pyridines: the Kondrat’eva Reaction2.2.1 Syntheses of Suaveoline and Norsuaveoline2.2.2 Synthesis of Eupolauramine2.2.3 Syntheses of (–)-Plectrodorine and (+)-Oxerine2.2.4 Synthesis of Amphimedine2.2.5 Synthetic Approach to the Western Segment of Haplophytine2.2.6 Synthesis of Marinoquinoline A2.2.6.1 IMDAO Approach to Marinoquinoline A2.2.6.2 Scope of Allenyl IMDAO Cycloaddition2.3 Lewis Acid Catalysis in IMDAO Reactions2.3.1 Effects of Europium Catalysts on IMDAO Reactions2.3.2 Effects of Copper Catalysts on IMDAO Reactions3 Imidazoles 4 Thiazoles4.1 Syntheses of Menthane and Eremophilane4.2 Further Comments on the Intramolecular Cycloadditions of Thiocarbonyl Ylides5 Conclusions and Outlook

scholarly journals Comparison of Corn Stover Pretreatments with Lewis Acid Catalyzed Choline Chloride, Glycerol and Choline Chloride-Glycerol Deep Eutectic Solvent

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1170
Author(s):  
Yuan Zhu ◽  
Benkun Qi ◽  
Xinquan Liang ◽  
Jianquan Luo ◽  
Yinhua Wan
Keyword(s):  
Corn Stover ◽  
Lewis Acid ◽  
Choline Chloride ◽  
Deep Eutectic Solvent ◽  
Enzymatic Saccharification ◽  
Glycerol Solution ◽  
Cellulose Conversion ◽  
Biomass Processing ◽  
Acid Catalyzed ◽  
Highly Correlated

Herein, corn stover (CS) was pretreated by less corrosive lewis acid FeCl3 acidified solutions of neat and aqueous deep eutectic solvent (DES), aqueous ChCl and glycerol at 120 °C for 4 h with single FeCl3 pretreatment as control. It was unexpected that acidified solutions of both ChCl and glycerol were found to be more efficient at removing lignin and xylan, leading to higher enzymatic digestibility of pretreated CS than acidified DES. Comparatively, acidified ChCl solution exhibited better pretreatment performance than acidified glycerol solution. In addition, 20 wt% water in DES dramatically reduced the capability of DES for delignification and xylan removal and subsequent enzymatic cellulose saccharification of pretreated CS. Correlation analysis showed that enzymatic saccharification of pretreated CS was highly correlated to delignification and cellulose crystallinity, but lowly correlated to xylan removal. Recyclability experiments of different acidified pretreatment solutions showed progressive decrease in the pretreatment performance with increasing recycling runs. After four cycles, the smallest decrease in enzymatic cellulose conversion (22.07%) was observed from acidified neat DES pretreatment, while the largest decrease (43.80%) was from acidified ChCl pretreatment. Those findings would provide useful information for biomass processing with ChCl, glycerol and ChCl-glycerol DES.

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