Boron Trifluoride Mediated Ring-Opening Reactions of trans-2-Aryl-3-nitro-cyclopropane-1,1-dicarboxylates. Synthesis of Aroylmethylidene Malonates as Potential Building Blocks for Heterocycles

2014 ◽  
Vol 79 (8) ◽  
pp. 3653-3658 ◽  
Author(s):  
Thangavel Selvi ◽  
Kannupal Srinivasan
Keyword(s):  
Ring Opening ◽  
Boron Trifluoride ◽  
Building Blocks ◽  
Ring Opening Reactions

scholarly journals Ring Opening of Donor–Acceptor Cyclopropanes with N-Nucleo­philes

Synthesis ◽  
2017 ◽  
Vol 49 (14) ◽  
pp. 3035-3068 ◽  
Author(s):  
Ekaterina Budynina ◽  
Konstantin Ivanov ◽  
Ivan Sorokin ◽  
Mikhail Melnikov
Keyword(s):  
Ring Opening ◽  
Building Blocks ◽  
Simple Approach ◽  
Secondary Amines ◽  
Primary Amines ◽  
Pyrrole Derivatives ◽  
Heteroaromatic Compounds ◽  
Azide Ion ◽  
Ring Opening Reactions ◽  
Donor Acceptor

Ring opening of donor–acceptor cyclopropanes with various N-nucleophiles provides a simple approach to 1,3-functionalized compounds that are useful building blocks in organic synthesis, especially in assembling various N-heterocycles, including natural products. In this review, ring-opening reactions of donor–acceptor cyclopropanes with amines, amides, hydrazines, N-heterocycles, nitriles, and the azide ion are summarized.1 Introduction2 Ring Opening with Amines3 Ring Opening with Amines Accompanied by Secondary Processes Involving the N-Center3.1 Reactions of Cyclopropane-1,1-diesters with Primary and Secondary Amines3.1.1 Synthesis of γ-Lactams3.1.2 Synthesis of Pyrroloisoxazolidines and -pyrazolidines3.1.3 Synthesis of Piperidines3.1.4 Synthesis of Azetidine and Quinoline Derivatives3.2 Reactions of Ketocyclopropanes with Primary Amines: Synthesis of Pyrrole Derivatives3.3 Reactions of Сyclopropane-1,1-dicarbonitriles with Primary Amines: Synthesis of Pyrrole Derivatives4 Ring Opening with Tertiary Aliphatic Amines5 Ring Opening with Amides6 Ring Opening with Hydrazines7 Ring Opening with N-Heteroaromatic Compounds7.1 Ring Opening with Pyridines7.2 Ring Opening with Indoles7.3 Ring Opening with Di- and Triazoles7.4 Ring Opening with Pyrimidines8 Ring Opening with Nitriles (Ritter Reaction)9 Ring Opening with the Azide Ion10 Summary

scholarly journals SnCl4-catalyzed Solvent-free Acetolysis of 2,7-Anhydrosialic Acid Derivatives

2019 ◽  
Author(s):  
Kesatebrhan Haile Asressu ◽  
Cheng-Chung Wang
Keyword(s):  
Sialic Acid ◽  
Lewis Acids ◽  
Ring Opening ◽  
Building Blocks ◽  
Solvent Free ◽  
Biologically Active ◽  
Protecting Group ◽  
Free Ring ◽  
Ring Opening Reactions ◽  
Acid Catalyzed

Sialic acid-containing glycans are found in different sialic acid forms and a variety of glycosidic linkages in biologically active glycoconjugates. Hence, the preparation of suitably protected sialyl building blocks requires high attention in order to access glycans in pure form. In this line, various C-5 substituted 2,7-anhydrosialic acid derivatives bearing both electron donating and withdrawing protecting groups were synthesized and subjected to different Lewis acid-catalyzed solvent free ring opening reactions at room temperature in the presence of acetic anhydride. Among the various Lewis acids tested, the desired acetolysized products were obtained in moderate yields under a tin(IV) chloride catalysis system. Our methodology can be extended to regioselective protecting group installation and manipulation towards a number of thiosialoside and halide donors.

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

Aminocyclitols. III. Synthesis of diaminocyclohexanediols

1979 ◽  
Vol 57 (14) ◽  
pp. 1870-1876 ◽  
Author(s):  
Gerry Kavadias ◽  
Robert Droghini
Keyword(s):  
Thionyl Chloride ◽  
Sodium Azide ◽  
Ring Opening ◽  
Boron Trifluoride ◽  
Boron Trifluoride Etherate ◽  
Reaction Sequence ◽  
Acidic Hydrolysis ◽  
Ring Opening Reactions ◽  
Cis And Trans ◽  
Hydrolysis Of

Reaction of N,N′-diethoxycarbonyl-2,5-dideoxystreptamine (1b) with thionyl chloride produced the iminoether dihydrochloride 8 which, upon simple treatment with water gave the di-N,O-carbonyl compound 9. Acidic hydrolysis of 9 yielded the aminocyclitol 2a. Alternatively, 2a was prepared from N,N′-dibenzoyl-2,5-dideoxystreptamine (1c) via the oxazoline 10 followed by acidic hydrolysis. Treatment of 1c with triethyl orthoacetate in the presence of boron trifluoride etherate produced the oxazoline 11 and the latter product was hydrolyzed to give 3a. By the same reaction sequence, 1e and 1h were converted to the oxazolines 12 and 13 which upon acidic hydrolysis provided the enantiomeric aminocyclitols 4 and 5. Ring-opening reactions of cis- and trans-1,4-diepoxycyclohexanes (14 and 16) with sodium azide to the diazido compounds 15 and 17, followed by reduction, afforded the aminocyclitols 6 and 7.

scholarly journals Fluorinated cyclohexanes: Synthesis of amine building blocks of the all-cis 2,3,5,6-tetrafluorocyclohexylamine motif

2017 ◽  
Vol 13 ◽  
pp. 728-733 ◽  
Author(s):  
Tetiana Bykova ◽  
Nawaf Al-Maharik ◽  
Alexandra M Z Slawin ◽  
David O'Hagan
Keyword(s):  
Methyl Iodide ◽  
Ring Opening ◽  
Building Blocks ◽  
Ring System ◽  
Cyclohexane Ring ◽  
Birch Reduction ◽  
Methyl Group ◽  
Ring Opening Reactions

This paper reports the synthesis of three amine stereoisomers 5a–c of the tetrafluorocyclohexyl ring system, as building blocks for discovery chemistry programmes. The synthesis starts from a Birch reduction of benzonitrile, followed by an in situ methyl iodide quench. The resultant 2,5-cyclohexadiene was progressed via double epoxidations and then hydrofluorination ring opening reactions. The resultant fluorohydrin moieties were then converted to different stereoisomers of the tetrafluorocyclohexyl ring system, and then reductive hydrogenation of the nitrile delivered three amine stereoisomers. It proved necessary to place a methyl group on the cyclohexane ring in order to stabilise the compound against subsequent HF elimination. The two all-cis tetrafluorocyclohexyl isomers 5a and 5b constitute facially polarized cyclohexane rings, with fluorines on the electronegative face and hydrogens on the electropositive face.

scholarly journals SnCl4-catalyzed solvent-free acetolysis of 2,7-anhydrosialic acid derivatives

2019 ◽  
Vol 15 ◽  
pp. 2990-2999
Author(s):  
Kesatebrhan Haile Asressu ◽  
Cheng-Chung Wang
Keyword(s):  
Sialic Acid ◽  
Lewis Acids ◽  
Ring Opening ◽  
Building Blocks ◽  
Solvent Free ◽  
Biologically Active ◽  
Protecting Group ◽  
Free Ring ◽  
Ring Opening Reactions ◽  
Acid Catalyzed

Sialic acid-containing glycans are found in different sialic acid forms and a variety of glycosidic linkages in biologically active glycoconjugates. Hence, the preparation of suitably protected sialyl building blocks requires high attention in order to access glycans in a pure form. In line with this, various C-5-substituted 2,7-anhydrosialic acid derivatives bearing both electron-donating and -withdrawing protecting groups were synthesized and subjected to different Lewis acid-catalyzed solvent-free ring-opening reactions at room temperature in the presence of acetic anhydride. Among the various Lewis acids tested, the desired acetolysis products were obtained in moderate yields under tin(IV) chloride catalysis. Our methodology could be extended to regioselective protecting group installations and manipulations towards a number of thiosialoside and halide donors.

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