scholarly journals Ring-Opening of Cyclodextrins: An Efficient Route to Pure Maltohexa-, Hepta-, and Octaoses

Organics ◽  
2021 ◽  
Vol 2 (3) ◽  
pp. 287-305
Author(s):  
Matthieu Pélingre ◽  
Dindet Steve-Evanes Koffi Teki ◽  
Jamal El-Abid ◽  
Vincent Chagnault ◽  
José Kovensky ◽  
...  
Keyword(s):  
Functional Groups ◽  
Organic Synthesis ◽  
Ring Opening ◽  
Building Blocks ◽  
Reaction Conditions ◽  
Strong Potential ◽  
Efficient Route ◽  
Biotechnological Processes

Many preparations of maltooligosaccharides have been described in literature, essentially using enzymatic or biotechnological processes. These compounds, derived from starch, are well-known as prebiotic agents. The use of maltohexa-, hepta-, and octaoses as synthons in organic synthesis was also well documented in literature. They can indeed be obtained as single compounds by the cyclodextrins’ ring-opening. This reaction has been studied for many years, varying the protecting and functional groups and the reaction conditions, leading to functionalized oligomaltoses. These compounds are of wide interest in various fields. They have a strong potential as scaffolds for multivalence in chemobiology, as building blocks for the production of biomimetic pseudo-glycopeptides, as well as monomers for the preparation of materials. In view of the importance of these oligomaltoses, this review focuses on the different methodologies allowing access to them via chemical and enzymatic ring-opening of cyclodextrins.

Electrophilic Ring Opening of Small Heterocycles

Synthesis ◽  
2017 ◽  
Vol 49 (24) ◽  
pp. 5307-5319 ◽  
Author(s):  
Chuan Wang
Keyword(s):  
Ethylene Oxide ◽  
Functional Groups ◽  
Organic Synthesis ◽  
Ring Opening ◽  
Building Blocks ◽  
Nickel Titanium ◽  
Ring Opening Reactions ◽  
Palladium Catalyzed ◽  
Ring Opening Of Epoxides ◽  
Nucleophilic Ring Opening

Small heterocycles, such as epoxides, aziridines, and ox­etanes are among the most useful building blocks in organic synthesis. Through electrophilic ring opening of these molecules, various electrophilic functional groups can be installed, which cannot be achieved via classic nucleophilic ring-opening reactions. In this review, the developments of electrophilic ring opening of small heterocycles are surveyed and organized according to the types of metal promoters.1 Introduction2 Electrophilic Ring Opening of Small Heterocycles Using Stoichiometric Metals2.1 Lithium-Mediated Electrophilic Ring Opening of Epoxides and Oxetanes2.2 Chromium-Mediated Electrophilic Ring Opening of Vinyl Epoxides2.3 Tin-Mediated Electrophilic Ring Opening of Vinyl Epoxides2.4 Samarium-Mediated Electrophilic Ring Opening of Vinyl and Alkynyl Epoxides2.5 Titanium-Mediated Electrophilic Ring Opening of Epoxides2.6 Platinum, Palladium, and Nickel-Mediated Electrophilic Ring Opening of 1,1-Dimethyl Ethylene Oxide3 Catalytic Electrophilic Ring Opening of Small Heterocycles3.1 Titanium-Catalyzed Electrophilic Ring Opening of Epoxides3.2 Palladium-Catalyzed Electrophilic Ring Opening of Vinyl and Alkynyl Small Heterocycles3.3 Iron-Catalyzed Electrophilic Ring Opening of Oxetanes3.4 Scandium-Catalyzed Electrophilic Ring Opening of Vinyl Epoxides3.5 Iridium-Catalyzed Electrophilic Ring Opening of 2-Methyl 2-Vinyl­oxiranes3.6 Nickel-Catalyzed Electrophilic Ring Opening of Epoxides and Aziridines3.7 Nickel–Titanium-Cocatalyzed Electrophilic Ring Opening of Epoxides4 Summary

scholarly journals Photoredox-catalyzed oxo-amination of aryl cyclopropanes

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Liang Ge ◽  
Ding-Xing Wang ◽  
Renyi Xing ◽  
Di Ma ◽  
Patrick J. Walsh ◽  
...  
Keyword(s):  
Organic Synthesis ◽  
Driving Force ◽  
Ring Opening ◽  
Bond Cleavage ◽  
Building Blocks ◽  
Nucleophilic Attack ◽  
Mechanistic Studies ◽  
Reaction Conditions ◽  
One Pot ◽  
Thermodynamic Driving Force

Abstract Cyclopropanes represent a class of versatile building blocks in modern organic synthesis. While the release of ring strain offers a thermodynamic driving force, the control of selectivity for C–C bond cleavage and the subsequent regiochemistry of the functionalization remains difficult, especially for unactivated cyclopropanes. Here we report a photoredox-coupled ring-opening oxo-amination of electronically unbiased cyclopropanes, which enables the expedient construction of a host of structurally diverse β-amino ketone derivatives. Through one electron oxidation, the relatively inert aryl cyclopropanes are readily converted into reactive radical cation intermediates, which in turn participate in the ensuing ring-opening functionalizations. Based on mechanistic studies, the present oxo-amination is proposed to proceed through an SN2-like nucleophilic attack/ring-opening manifold. This protocol features wide substrate scope, mild reaction conditions, and use of dioxygen as an oxidant both for catalyst regeneration and oxygen-incorporation. Moreover, a one-pot formal aminoacylation of olefins is described through a sequential cyclopropanation/oxo-amination.

Synthesis and Applications of Cyclopropanones and their Equivalents as Three-Carbon Building Blocks in Organic Synthesis

Synthesis ◽  
2021 ◽  
Author(s):  
Yujin Jang ◽  
Roger Machin-Rivera ◽  
Vincent Lindsay
Keyword(s):  
Organic Synthesis ◽  
Ring Opening ◽  
Building Blocks ◽  
Ring Expansion ◽  
Ring System ◽  
Small Ring ◽  
Future Directions ◽  
Highly Strained ◽  
And Storage

Cyclopropanone derivatives constitute highly strained cycloalkanones with promising applications as three-carbon building blocks in organic synthesis. Due to the presence of a ketone in such a small ring system, all C–C bonds and the carbonyl group are considered to be labile in suitable conditions, leading to a wide variety of synthetic disconnections, including nucleophilic addition, ring expansion, ring-opening and (formal) cycloaddition. Despite their synthetic potential, the widespread adoption of cyclopropanones as substrates has been considerably hampered by the difficulties associated with the preparation and storage of such unstable compounds, prompting the development of cyclopropanone surrogates that can equilibrate to parent ketone in situ via elimination. This review summarizes the syntheses and applications of cyclopropanone derivatives and their equivalents, and offers a perspective of the state of the field as well as its expected future directions.

Silylboranes as Powerful Tools in Organic Synthesis: Stereo- and Regioselective Reactions with 1,n-Enynes

Synthesis ◽  
2020 ◽  
Vol 52 (21) ◽  
pp. 3129-3139 ◽  
Author(s):  
Christina Moberg
Keyword(s):  
Metal Complexes ◽  
Functional Groups ◽  
Organic Synthesis ◽  
Building Blocks ◽  
Subsequent Transformation ◽  
Element Addition ◽  
Regioselective Reactions ◽  
Group 10

Bismetalated alkenes, accessible by element–element addition to alkynes, are valuable building blocks in organic synthesis, providing wide opportunities for divergent synthesis. Silaboration of alkynes with a pendant olefinic group, catalyzed by group 10 metal complexes, and subsequent transformation of the silicon and boron functional groups give access to densely functionalized 1,3-dienes and 1,3,5-trienes with defined stereo- and regiochemistry, 1,2-dienes, and carbocyclic and heterocyclic products.1 Introduction2 Background3 Reactions with 1,3-Enynes4 Cyclization 1,6-Enynes5 Cyclization 1,7-Enynes6 Cyclization of 1,n-Enynes (n > 7)7 Cyclization of Dienynes and Enediynes8 Cyclization of 1,6-Diynes9 Conclusions

scholarly journals Asymmetric Ring-Opening of Epoxides Catalyzed by Metal–Salen Complexes

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 705
Author(s):  
Anna Lidskog ◽  
Yutang Li ◽  
Kenneth Wärnmark
Keyword(s):  
Functional Groups ◽  
Organic Synthesis ◽  
Ring Opening ◽  
Kinetic Resolution ◽  
Catalytic Systems ◽  
Salen Complexes ◽  
Epoxide Opening ◽  
Ring Opening Of Epoxides ◽  
One Step ◽  
Asymmetric Ring Opening

The asymmetric ring-opening of epoxides is an important reaction in organic synthesis, since it allows for the enantioselective installation of two vicinal functional groups with specific stereochemistry within one step from a highly available starting material. An effective class of catalysts for the asymmetric ring-opening of epoxides is metal–salen complexes. This review summarizes the development of metal–salen catalyzed enantioselective desymmetrization of meso-epoxides and kinetic resolution of epoxides with various nucleophiles, including the design and application of both homogeneous- and heterogeneous epoxide-opening catalysts as well as multi-metallic covalent and supramolecular catalytic systems.

Regioselective N-alkylation of (2-chloroquinolin-3-yl) methanol with N-heterocyclic compounds using the Mitsunobu reagent

2011 ◽  
Vol 65 (3) ◽  
Author(s):  
Selvaraj Roopan ◽  
Fazlur-Rahman Khan ◽  
Jong Jin
Keyword(s):  
Natural Product ◽  
Organic Synthesis ◽  
Heterocyclic Compounds ◽  
Building Blocks ◽  
Natural Product Synthesis ◽  
Mitsunobu Reaction ◽  
Reaction Conditions ◽  
Diethyl Azodicarboxylate ◽  
Nitrogen Heterocyclic

AbstractThe Mitsunobu reaction is a well-established fundamental reaction and has been widely applied in organic synthesis. In this paper, under Mitsunobu conditions dehydration proceeds between (2-chloroquinolin-3-yl)methanol and nitrogen heterocyclic compounds such as quinazolinone, pyrimidone, 2-oxoquinoline in dry THF in the presence of triethylamine, triphenylphosphane and diethyl azodicarboxylate to give the corresponding products. As part of our recent research, we attempted to couple two N-heterocyclic compounds under Mitsunobu reaction conditions to provide efficient building blocks for natural product synthesis.

Carbenoid-Mediated Homologation Tactics for Assembling (Fluorinated) Epoxides and Aziridines

Synlett ◽  
2020 ◽  
Author(s):  
Laura Ielo ◽  
Vittorio Pace ◽  
Veronica Pillari ◽  
Margherita Miele ◽  
Davide Castiglione
Keyword(s):  
Case Studies ◽  
Organic Synthesis ◽  
Building Blocks ◽  
Carbon Skeleton ◽  
Illustrative Case ◽  
Reaction Conditions ◽  
Structural Motifs ◽  
Fluorinated Building Blocks ◽  
Single Operation

Homologation strategies provide highly versatile tools in organic synthesis for the introduction of a CH2 group into a given carbon skeleton. The operation can result in diverse structural motifs by tuning of the reaction conditions and the nature of the homologating agent. In this Account, concisely contextualizing our work with lithium carbenoids (LiCH2X, LiCHXY etc) for homologating carbon-centered electrophiles, we focus on the assembly of three-membered cycles featuring fluorinated substituents. Two illustrative case studies are considered: (1) the development and employment of fluorinated carbenoids en route to rare α-fluoroepoxides and aziridines, and (2) the installation of up to halomethylenic groups on trifluoroimidoylacetyl chlorides (TFAICs) for preparing CF3-containing halo- and halomethylaziridines. Collectively, we demonstrate that the initial homologation event generated by the installation of the carbenoid, upon modulation of the conditions, serves as a tool for creating fluorinated building blocks in a single operation.

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