Enantioselective formation and ring-opening of epoxides catalysed by halohydrin dehalogenases

2006 ◽  
Vol 34 (2) ◽  
pp. 291-295 ◽  
Author(s):  
D.B. Janssen ◽  
M. Majerić-Elenkov ◽  
G. Hasnaoui ◽  
B. Hauer ◽  
J.H. Lutje Spelberg
Keyword(s):  
Ring Opening ◽  
Building Blocks ◽  
Epoxide Ring ◽  
Structural Studies ◽  
Halide Ions ◽  
Catalytic Promiscuity ◽  
Agrobacterium Radiobacter ◽  
Enzymatic Production ◽  
Ring Opening Reactions ◽  
Ring Opening Of Epoxides

Halohydrin dehalogenases catalyse the conversion of vicinal halohydrins into their corresponding epoxides, while releasing halide ions. They can be found in several bacteria that use halogenated alcohols or compounds that are degraded via halohydrins as a carbon source for growth. Biochemical and structural studies have shown that halohydrin dehalogenases are evolutionarily and mechanistically related to enzymes of the SDR (short-chain dehydrogenase/reductase) superfamily. In the reverse reaction, which is epoxide-ring opening, different nucleophiles can be accepted, including azide, nitrite and cyanide. This remarkable catalytic promiscuity allows the enzymatic production of a broad range of β-substituted alcohols from epoxides. In these oxirane-ring-opening reactions, the halohydrin dehalogenase from Agrobacterium radiobacter displays high enantioselectivity, making it possible to use the enzyme for the preparation of enantiopure building blocks for fine chemicals.

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

Aluminium triflate as catalyst for epoxide ring-opening and esterification reactions — Mechanistic aspects

2005 ◽  
Vol 83 (6-7) ◽  
pp. 854-861 ◽  
Author(s):  
Yvette M Terblans ◽  
Johannes J Huyser ◽  
Michelle Huyser ◽  
Michael J Green ◽  
Desmond A Young ◽  
...  
Keyword(s):  
Ring Opening ◽  
Epoxide Ring ◽  
Epoxide Ring Opening ◽  
Low Concentrations ◽  
Ring Opening Reactions ◽  
Ring Opening Of Epoxides ◽  
Molecular Modeling Studies ◽  
Esterification Reactions ◽  
Active Intermediates ◽  
Formation Energies

Al(CF3SO3)3 is a highly effective catalyst for the ring opening of epoxides with methanol, as well as for the esterification of carboxylic acids with alcohols. Factors that influence the rate of the ring opening of butene oxide with methanol and the esterification of acetic acid with n-propanol and ethanol were investigated. It was found that low concentrations (e.g., ~5 ppm) of Al(CF3SO3)3 catalyze the ring-opening reactions, whereas considerably higher concentrations are required for esterification reactions. Molecular modeling studies suggest that these differences can be rationalized in terms of the formation energies of the active intermediates of these reactions.Key words: epoxide, ring opening, esterification, aluminium triflate.

Polyoxometalate-modified reduced graphene oxide foam as a monolith reactor for efficient flow catalysis of epoxide ring-opening reactions

2021 ◽  
Vol 9 (13) ◽  
pp. 8480-8488
Author(s):  
Xiaoting Jing ◽  
Zhen Li ◽  
Weijie Geng ◽  
Hongjin Lv ◽  
Yingnan Chi ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Broad Spectrum ◽  
Ring Opening ◽  
Epoxide Ring ◽  
Turnover Number ◽  
Epoxide Ring Opening ◽  
Monolith Reactor ◽  
Reduced Graphene ◽  
Ring Opening Reactions ◽  
Hydrothermal Approach

A POM@rGO monolith reactor was constructed using a facile and broad-spectrum hydrothermal approach and it effectively catalyzes epoxide ring-opening reactions with 99% conversion and over 90% selectivity, reaching a turnover number (TON) of around 28 044 after 38 h catalysis.

Fiber-supported Fe(iii) complex catalyst in spinning basket reactor for cleaner ring-opening of epoxides with alcohols

2019 ◽  
Vol 21 (13) ◽  
pp. 3573-3582 ◽  
Author(s):  
Xian-Lei Shi ◽  
Benyu Sun ◽  
Qianqian Hu ◽  
Yongju Chen ◽  
Peigao Duan
Keyword(s):  
Ring Opening ◽  
Complex Catalyst ◽  
Ring Opening Reactions ◽  
Ring Opening Of Epoxides

An available, nontoxic, efficient, recyclable and gram-scaleable fiber-supported Fe(iii) complex catalyst in spinning basket reactor for cleaner ring-opening reactions.

Intramolecular Guanidine Epoxide Ring Opening Reactions.

ChemInform ◽  
2003 ◽  
Vol 34 (27) ◽  
Author(s):  
Mark Dennis ◽  
Louise M. Hall ◽  
Patrick J. Murphy ◽  
Andrew J. Thornhill ◽  
Robert Nash ◽  
...  
Keyword(s):  
Ring Opening ◽  
Epoxide Ring ◽  
Epoxide Ring Opening ◽  
Ring Opening Reactions

Active Copper Catalyzed Regioselective Ring Opening of Epoxides by Heterocyclic Amines: An Efficient Protocol for Synthesis of β-Amino Alcohols

2019 ◽  
Vol 4 (3) ◽  
pp. 194-199
Author(s):  
Santosh S. Devkate ◽  
Arvind S. Burungale ◽  
Ashok S. Pise ◽  
Sunil D. Jadhav
Keyword(s):  
Natural Products ◽  
Carbon Atom ◽  
Ring Opening ◽  
Amino Alcohols ◽  
Heterocyclic Amines ◽  
Epoxide Ring ◽  
Epoxide Ring Opening ◽  
Ring Opening Of Epoxide ◽  
Ring Opening Of Epoxides

The regioselective epoxide ring opening at less substituted carbon atom of epoxide were reported by nucleophiles like heterocyclic amines which gives well known 1,2-difunctionalized amino alcohols. These are present in many synthetic as well as natural products. The ring opening of epoxide is achieved by cleavage with amines in presence of copper(0) as a catalyst. It is observed that the lithium napthalenide reduction of copper(I) produces a highly reactive form of copper(0) that acts as a catalyst for ring opening of epoxides with an amine.

Graphene oxide as a catalyst for ring opening reactions in amine crosslinking of epoxy resins

RSC Advances ◽  
2016 ◽  
Vol 6 (28) ◽  
pp. 23858-23865 ◽  
Author(s):  
M. R. Acocella ◽  
C. Esposito Corcione ◽  
A. Giuri ◽  
M. Maggio ◽  
A. Maffezzoli ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Bisphenol A ◽  
Ring Opening ◽  
Epoxy Resins ◽  
Diglycidyl Ether ◽  
Epoxide Ring ◽  
Epoxide Ring Opening ◽  
Ring Opening Reactions

The influence of different graphite-based nanofillers on epoxide ring opening reactions, as induced by amines for diglycidyl ether of bisphenol A (DGEBA), is studied.

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