ChemInform Abstract: An Epoxide Ring-Opening Approach for a Short and Stereoselective Synthesis of Icetexane Diterpenoids.

ChemInform ◽  
2010 ◽  
Vol 41 (17) ◽  
Author(s):  
Adriana Carita ◽  
Antonio C. B. Burtoloso
Keyword(s):  
Ring Opening ◽  
Stereoselective Synthesis ◽  
Epoxide Ring ◽  
Epoxide Ring Opening

scholarly journals Regio- and stereoselective synthesis of new diaminocyclopentanols

2014 ◽  
Vol 10 ◽  
pp. 2513-2520 ◽  
Author(s):  
Evgeni A Larin ◽  
Valeri S Kochubei ◽  
Yuri M Atroshchenko
Keyword(s):  
Nitrogen Atom ◽  
Ring Opening ◽  
Stereoselective Synthesis ◽  
Alternative Pathway ◽  
Acid Catalyst ◽  
Epoxide Ring ◽  
Optimal Conditions ◽  
Epoxide Ring Opening ◽  
Lewis Acid Catalyst ◽  
Nucleophilic Reagents

The optimal conditions for regio- and stereoselective epoxide ring opening of N,N-disubstituted 1,2-epoxy-3-aminocyclopentanes by different nucleophilic reagents have been developed. The substituents on the nitrogen atom in the epoxide precursor and the orientation of the oxirane ring are crucial for the reaction outcome. Thus, treatment of (1RS,2SR,3SR)-1,2-epoxy-3-(N,N-dibenzylamino)cyclopentane (3b) with amines gave a mixture of C1 and C2 regioadducts, while the use of (1RS,2SR,3SR)-1,2-epoxy-3-(N-benzyl-N-methylamino)cyclopentane (3a) led ultimately to C1 adducts. Base-catalyzed aminolysis of epoxides 6a,b afforded mainly C1 adducts 13a,b arising from trans-diaxal opening of the epoxide ring. Using a Lewis acid catalyst, epoxides 6a,b were transformed into diaminocyclopentanols 14a,b via an alternative pathway involving the formation of aziridinium intermediate 17.

Bimetallic Radical Redox-Relay Catalysis for the Isomerization of Epoxides to Allylic Alcohols

2019 ◽  
Author(s):  
Ke-Yin Ye ◽  
Terry McCallum ◽  
Song Lin
Keyword(s):  
Ring Opening ◽  
High Reactivity ◽  
Hydrogen Atom Transfer ◽  
Organic Radicals ◽  
Epoxide Ring ◽  
Allylic Alcohols ◽  
Epoxide Ring Opening ◽  
Bond Forming ◽  
Co Catalysts ◽  
The Rich

Organic radicals are generally short-lived intermediates with exceptionally high reactivity. Strategically, achieving synthetically useful transformations mediated by organic radicals requires both efficient initiation and selective termination events. Here, we report a new catalytic strategy, namely bimetallic radical redox-relay, in the regio- and stereoselective rearrangement of epoxides to allylic alcohols. This approach exploits the rich redox chemistry of Ti and Co complexes and merges reductive epoxide ring opening (initiation) with hydrogen atom transfer (termination). Critically, upon effecting key bond-forming and -breaking events, Ti and Co catalysts undergo proton-transfer/electron-transfer with one another to achieve turnover, thus constituting a truly synergistic dual catalytic system.<br>

Construction the A-B bicyclic ring structure of Stemocurtisisne

2020 ◽  
Vol 17 ◽  
Author(s):  
Duc Dau Xuan
Keyword(s):  
Glutamic Acid ◽  
Natural Product ◽  
Mannich Reaction ◽  
Boronic Acid ◽  
Ring Opening ◽  
Ring Structure ◽  
Starting Material ◽  
Epoxide Ring ◽  
Epoxide Ring Opening

: The synthesis of the A-B bicyclic ring structure 3 of the natural product Stemocurtisine is described. The synthesis was accomplished in seven synthetic steps from commercially available L-glutamic acid. The key step involved a borono-Mannich reaction between the hemiaminal 6 and trans-β-styryl boronic acid and trans-β-styrylpotassiumtrifluoroborate to prepare the cis diene 4. Attempts to prepare the A-B-C ring compound 2 via intramolecular epoxide ring opening followed by rearangement under different basic conditions were unsuccessful. Only unreactive starting material was recovered.

scholarly journals Thermal and Electrochemical Properties of Solid Polymer Electrolytes Prepared via Lithium Salt-Catalyzed Epoxide Ring Opening Polymerization

2021 ◽  
Vol 11 (4) ◽  
pp. 1561
Author(s):  
Gabrielle Foran ◽  
Nina Verdier ◽  
David Lepage ◽  
Arnaud Prébé ◽  
David Aymé-Perrot ◽  
...  
Keyword(s):  
Electrochemical Properties ◽  
Polymer Electrolytes ◽  
Ring Opening ◽  
Lithium Salt ◽  
Ring Opening Polymerization ◽  
Solid Polymer Electrolytes ◽  
Solid Polymer ◽  
Polymerization Reaction ◽  
Epoxide Ring ◽  
Epoxide Ring Opening

Solid polymer electrolytes have been widely proposed for use in all solid-state lithium batteries. Advantages of polymer electrolytes over liquid and ceramic electrolytes include their flexibility, tunability and easy processability. An additional benefit of using some types of polymers for electrolytes is that they can be processed without the use of solvents. An example of polymers that are compatible with solvent-free processing is epoxide-containing precursors that can form films via the lithium salt-catalyzed epoxide ring opening polymerization reaction. Many polymers with epoxide functional groups are liquid under ambient conditions and can be used to directly dissolve lithium salts, allowing the reaction to be performed in a single reaction vessel under mild conditions. The existence of a variety of epoxide-containing polymers opens the possibility for significant customization of the resultant films. This review discusses several varieties of epoxide-based polymer electrolytes (polyethylene, silicone-based, amine and plasticizer-containing) and to compare them based on their thermal and electrochemical properties.

ChemInform Abstract: NEIGHBORING GROUP EFFECTS IN EPOXIDE RING OPENING, CIS-EPOXY-ALCOHOLS

1976 ◽  
Vol 7 (42) ◽  
pp. no-no
Author(s):  
ERWIN GLOTTER ◽  
PNINA KRINSKY ◽  
MIRIAM REJTOE ◽  
MARTIN WEISSENBERG
Keyword(s):  
Ring Opening ◽  
Epoxide Ring ◽  
Neighboring Group ◽  
Epoxide Ring Opening ◽  
Epoxy Alcohols ◽  
Group Effects

An analysis of the factors contributing to the regioselectivity observed in the opening of oxiranes

1980 ◽  
Vol 58 (3) ◽  
pp. 302-306 ◽  
Author(s):  
Margaret M. Kayser ◽  
Peter Morand
Keyword(s):  
Oxygen Atom ◽  
Ring Opening ◽  
Oxirane Ring ◽  
Epoxide Ring ◽  
Acid Base ◽  
Epoxide Ring Opening ◽  
Soft Acid ◽  
Hsab Theory

The regioselectivity of epoxide ring opening can be analyzed in terms of hard–soft acid–base (HSAB) theory. The coordination of the hard acid with the oxygen atom of the oxirane ring produces a "pulling effect" which determines the direction of the ring opening. In the absence of a strong "pulling effect" the "pushing effect" of the approaching base is examined and the consequences of relative softness or hardness of the nucleophile on the regioselectivity of the ring opening are discussed.

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