scholarly journals Relay Cross Metathesis for the Iterative Ascent of the Terpenoids

2019 ◽  
Author(s):  
Karim Bahou ◽  
D. Christopher Braddock ◽  
Adam G. Meyer ◽  
G. Paul Savage ◽  
Zhensheng Shi
Keyword(s):  
Natural Products ◽  
Functional Group ◽  
Building Blocks ◽  
Design And Implementation ◽  
Cross Metathesis ◽  
Naturally Occurring ◽  
Trisubstituted Olefins

<div>We report the design and implementation of a relay cross</div><div>metathesis (ReXM) reaction for the ascent of the terpenoids in an iterative protocol. The method features the reaction of naturally occurring terpenoid building blocks – with preexisting trisubstituted olefins – which combine to construct a new trisubstituted olefin resulting in a five-carbon unit homologation. Subsequent functional group manipulation allows for the method to be repeated in an</div><div>iterative fashion. The method is used for the synthesis of a diterpenebenzoate macrolide of biogenetic relevance to the bromophycolide family of natural products.</div>

Relay Cross Metathesis for the Ascent of the Terpenoids

2019 ◽  
Author(s):  
Karim Bahou ◽  
D. Christopher Braddock ◽  
Adam G. Meyer ◽  
G. Paul Savage ◽  
Zhensheng Shi
Keyword(s):  
Natural Products ◽  
Building Blocks ◽  
Design And Implementation ◽  
Cross Metathesis ◽  
Naturally Occurring

We report the design and implementation of a relay cross metathesis (ReXM) reaction for the ascent of the terpenoids in an iterative protocol using naturally occurring terpenoid building blocks. The method is used for the synthesis of a diterpene-benzoate macrolide of biogenetic relevance to the bromophycolide family of natural products.

An Atom-Economic and Stereospecific Access to Trisubstituted Olefins through Enyne Cross Metathesis Followed by 1,4-Hydrogenation

Synlett ◽  
2018 ◽  
Vol 29 (06) ◽  
pp. 785-792 ◽  
Author(s):  
Hans-Günther Schmalz ◽  
Friederike Ratsch
Keyword(s):  
Functional Group ◽  
Cross Metathesis ◽  
Broad Scope ◽  
Trisubstituted Olefins

The combination of intermolecular enyne cross metathesis and subsequent 1,4-hydrogenation opens a stereocontrolled and atom-economic access to trisubstituted olefins. By investigating different combinations of functionalized alkyne and alkene substrates, we found that the outcome (yield, E/Z ratio) of the Grubbs II-catalyzed enyne cross-metathesis step depends on the substrate’s structure, the amount of the alkene (used in excess), and the (optional) presence of ethylene. In any case, the 1,4-hydrogenation, catalyzed by 1,2-di­methoxybenzene-Cr(CO)3, proceeds stereospecifically to yield exclusively the E-products from both the E- and Z-1,3-diene intermediates obtained by metathesis. A rather broad scope and functional group compatibility of the method is demonstrated by means of 15 examples.

scholarly journals Chiral Alkyl Amine Synthesis via Catalytic Enantioselective Hydroalkylation of Enamides

2020 ◽  
Author(s):  
Deyun Qian ◽  
Srikrishna Bera ◽  
Xile Hu
Keyword(s):  
Natural Products ◽  
Functional Group ◽  
Building Blocks ◽  
Alkyl Halides ◽  
Enantioselective Synthesis ◽  
Mild Conditions ◽  
Drug Molecules ◽  
Alkyl Amines ◽  
Wide Range ◽  
Synthetic Intermediates

Chiral alkyl amines are omnipresent as bio-active molecules and synthetic intermediates. Catalytic and enantioselective synthesis of alkyl amines from readily accessible precursors is challenging. Here we develop a nickel-catalyzed hydroalkylation method to assemble a wide range of chiral alkyl amines from enamides and alkyl halides in high regio- and enantioselectivity. The method works for both non-activated and activated alkyl halides, and is able to produce enantiomerically enriched amines with two minimally differentiated alpha-alkyl substituents. The mild conditions lead to high functional group tolerance, which is demonstrated in the post-product functionalization of many natural products and drug molecules, as well as the synthesis of chiral building blocks and key intermediates to bio-active compounds.

scholarly journals Chiral Alkyl Amine Synthesis via Catalytic Enantioselective Hydroalkylation of Enamides

2020 ◽  
Author(s):  
Deyun Qian ◽  
Srikrishna Bera ◽  
Xile Hu
Keyword(s):  
Natural Products ◽  
Functional Group ◽  
Building Blocks ◽  
Alkyl Halides ◽  
Enantioselective Synthesis ◽  
Mild Conditions ◽  
Drug Molecules ◽  
Alkyl Amines ◽  
Wide Range ◽  
Synthetic Intermediates

Chiral alkyl amines are omnipresent as bio-active molecules and synthetic intermediates. Catalytic and enantioselective synthesis of alkyl amines from readily accessible precursors is challenging. Here we develop a nickel-catalyzed hydroalkylation method to assemble a wide range of chiral alkyl amines from enamides and alkyl halides in high regio- and enantioselectivity. The method works for both non-activated and activated alkyl halides, and is able to produce enantiomerically enriched amines with two minimally differentiated alpha-alkyl substituents. The mild conditions lead to high functional group tolerance, which is demonstrated in the post-product functionalization of many natural products and drug molecules, as well as the synthesis of chiral building blocks and key intermediates to bio-active compounds.

scholarly journals General Electrochemical Minisci Alkylation of N-Heteroarenes with Alkyl Halides

2022 ◽  
Author(s):  
Jose Aleman
Keyword(s):  
Natural Products ◽  
Functional Group ◽  
Environmentally Friendly ◽  
Building Blocks ◽  
Alkyl Halides ◽  
Alkyl Radicals ◽  
First Time ◽  
Very High ◽  
Tertiary Alkyl

Abstract Herein, we report, for the first time, a general, facile and environmentally friendly Minisci-type alkylation of N-heteroarenes under simple and straightforward electrochemical conditions using widely available alkyl halides as radical precursors. Primary, secondary and tertiary alkyl radicals have shown to be efficiently generated and coupled with a large variety of N-heteroarenes. The method presents a very high functional group tolerance, including various heterocyclic-based natural products, which highlights the robustness of the methodology. This applicability has been further proved in the synthesis of various interesting biologically valuable building blocks. In addition, we have proposed a mechanism based on different proofs and electrochemical evidences.

Terpenoids as Renewable Nano-Sized Building Blocks

2017 ◽  
Vol 1 (3) ◽  
Author(s):  
Braja Gopal Bag ◽  
Abir Chandan Barai ◽  
Sk Nurul Hasan ◽  
Subhajit Das ◽  
Chhabi Garai ◽  
...  
Keyword(s):  
Natural Products ◽  
Molecular Mechanics ◽  
Building Blocks ◽  
Heat Of Formation ◽  
Naturally Occurring ◽  
Molecular Mechanics Calculation

Terpenoids are a large and structurally group of natural products containing multiple five carbon containing isoprene units. Previously we have reported that irrespective of their acyclic or alicyclic nature, all the triterpenoids containing 30C’s have nano-metric lengths. In the current studies, detailed computations have been carried out with 120 naturally occurring mono- (C10), sesqui- (C15), di- (C20), sester- (C25), sesqua- (C35) and tetra- (C40) terpenoids using Gaussian 09 software with Gauss view 07 and molecular mechanics calculation using Serena software. The heat of formation and the calculated molecular lengths obtained by the two methods were compared. Interestingly, monoterpenoid to tetraterpenoid all the terpenoids (except three monoterpenoid and one sesqui-terpenoid) have molecular lengths above one nanometer making them useful as nano-sized building blocks.

Formation of Carbon-Oxygen Bond Mediated by Hypervalent Iodine Reagents Under Metal-free Conditions

2020 ◽  
Vol 17 ◽  
Author(s):  
Ayesha Jalil ◽  
Yaxin O Yang ◽  
Zhendong Chen ◽  
Rongxuan Jia ◽  
Tianhao Bi ◽  
...  
Keyword(s):  
Natural Products ◽  
Bond Formation ◽  
Building Blocks ◽  
Review Article ◽  
Hypervalent Iodine ◽  
Metal Free ◽  
Bioactive Natural Products ◽  
The Past ◽  
Oxygen Bond ◽  
Privileged Scaffolds

: Hypervalent iodine reagents are a class of non-metallic oxidants have been widely used in the construction of several sorts of bond formations. This surging interest in hypervalent iodine reagents is essentially due to their very useful oxidizing properties, combined with their benign environmental character and commercial availability from the past few decades ago. Furthermore, these hypervalent iodine reagents have been used in the construction of many significant building blocks and privileged scaffolds of bioactive natural products. The purpose of writing this review article is to explore all the transformations in which carbon-oxygen bond formation occurred by using hypervalent iodine reagents under metal-free conditions

scholarly journals Non-Enzymatic Desymmetrization Reactions in Aqueous Media

Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 720
Author(s):  
Satomi Niwayama
Keyword(s):  
Natural Products ◽  
Total Synthesis ◽  
Functional Groups ◽  
Organic Compounds ◽  
Recent Progress ◽  
Aqueous Media ◽  
Building Blocks ◽  
Organic Reactions ◽  
Environmentally Benign ◽  
Enzymatic Desymmetrization

Symmetric organic compounds are generally obtained inexpensively, and therefore they can be attractive building blocks for the total synthesis of various pharmaceuticals and natural products. The drawback is that discriminating the identical functional groups in the symmetric compounds is difficult. Water is the most environmentally benign and inexpensive solvent. However, successful organic reactions in water are rather limited due to the hydrophobicity of organic compounds in general. Therefore, desymmetrization reactions in aqueous media are expected to offer versatile strategies for the synthesis of a variety of significant organic compounds. This review focuses on the recent progress of desymmetrization reactions of symmetric organic compounds in aqueous media without utilizing enzymes.

scholarly journals Chemical Diversity of Plant Cyanogenic Glycosides: An Overview of Reported Natural Products

Molecules ◽  
2021 ◽  
Vol 26 (3) ◽  
pp. 719
Author(s):  
Meri Yulvianti ◽  
Christian Zidorn
Keyword(s):  
Natural Products ◽  
Plant Species ◽  
Chemical Diversity ◽  
Cyanogenic Glycosides ◽  
Sugar Moiety ◽  
Plant Natural Products ◽  
Naturally Occurring

Cyanogenic glycosides are an important and widespread class of plant natural products, which are however structurally less diverse than many other classes of natural products. So far, 112 naturally occurring cyanogenic glycosides have been described in the phytochemical literature. Currently, these unique compounds have been reported from more than 2500 plant species. Natural cyanogenic glycosides show variations regarding both the aglycone and the sugar part of the molecules. The predominant sugar moiety is glucose but many substitution patterns of this glucose moiety exist in nature. Regarding the aglycone moiety, four different basic classes can be distinguished, aliphatic, cyclic, aromatic, and heterocyclic aglycones. Our overview covers all cyanogenic glycosides isolated from plants and includes 33 compounds with a non-cyclic aglycone, 20 cyclopentane derivatives, 55 natural products with an aromatic aglycone, and four dihydropyridone derivatives. In the following sections, we will provide an overview about the chemical diversity known so far and mention the first source from which the respective compounds had been isolated. This review will serve as a first reference for researchers trying to find new cyanogenic glycosides and highlights some gaps in the knowledge about the exact structures of already described compounds.

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