Ring-Opening Reactions Of Aziridines Research Articles

Step-growth Polymerization of Aziridines with Elemental Sulfur: Easy Access to Linear Polysulfides and Their Use as Recyclable Adhesives.

The bulk radical polymerization of bis(aziridine) with molten elemental sulfur resulted in brittle, cross-linked polymers. However, when the bis(aziridine) was treated with elemental sulfur in the presence of an organobase, the ring-opening reaction of aziridine with oligosulfide anions occurred, leading to the formation of linear polymers by step-growth polymerization. These newly synthesized polymers possess repeating units containing a sulfonamide or amide functional moiety and oligosulfide bonds with an average sulfur segment of about two. A small molecular model reaction confirmed the nucleophilic addition reaction of elemental sulfur to aziridine. It was verified that S-S dynamic bond exchange takes place in the presence of an organic base within the linear chains. The mixture of the synthesized polysulfides with pyridine exhibits exceptional adhesive properties when applied to steel, and aluminum substrates. Notably, these prepared adhesives displayed good reusability due to the dynamic S-S exchange and complete recyclability due to their solution processability. This elemental sulfur-involved polymerization approach represents an innovative method for the synthesis of advanced sulfur-containing polymers, demonstrating the potential for various applications in adhesives and beyond.

Base mediated aza-[2 + 1] annulation and regioselective aziridine ring-opening cascade: mild synthesis of functionalized β-amino ketones from cyclic N-sulfonyl aldimines and α-carbonyl sulfonium salts.

Cyclic N-sulfonyl aldimines are well-known aza-[2C]-synthons for various [2 + n] annulation reactions. Herein we describe a novel base mediated [2 + 1] annulation and a regioselective aziridine ring-opening reaction cascade, which provides an efficient and distinct synthetic strategy from readily available cyclic N-sulfonyl aldimines and α-carbonyl sulfonium salts leading to β-amino ketone derivatives through the corresponding fused tri-substituted aziridines. This one-pot, two-step process involves formation of C-C and C-N bonds and subsequent cleavage of a C-N bond. The features of the developed reaction include the use of mild reaction conditions, broad substrate scope, and excellent yields. The synthetic utility of this approach was demonstrated by gram-scale operation and further product derivatizations.

Synthetic Strategies of N-Heterocyclic Olefin (NHOs) and Their Recent Application of Organocatalytic Reactions and Beyond.

N-heterocyclic olefins (NHOs) derivatives have an electron-rich as well as highly polarized carabon-carbon (C=C) double bond because of the electron-donating nature of nitrogen and sulphur atoms. While NHOs have been developing as novel organocatalysts and ligands for transition metal complexes in various organic compound syntheses, different research groups are currently interested in preparing imidazole and triazolium-based chiral NHO catalysts. Some of them have been used for enantioselective organic transformations, but were still elusive. N-Heterocyclic Olefins, the alkylidene derivatives of N-heterocyclic carbenes (NHC) have shown promising results as effective promoters for numerous organic syntheses such as asymmetric catalysis, hydroborylation, hydrosilylation, reduction, CO2 sequestration, alkylation, cycloaddition, polymerization and the ring-opening reaction of aziridine and epoxides, esterification, C-F bond functionalization, amine coupling, trifluoromethyl thiolation, amination etc. NHOs catalysts with suitable structure can serve as a novel class of Lewis/Bronsted bases with strong basicity and high nucleophilicity properties. These facts strongly suggest their enormous chemical potential as sustainable catalysts for a wide variety of reactions in synthetic chemistry. The synthesis of NHOs and their properties are briefly reviewed in this article, along with a summary of the imidazole and triazole core of NHOs' most recent catalytic uses.

Nickel-Catalyzed Cross-Electrophile Ring Opening/gem-Difluoroallylation of Aziridines.

Herein we report a nickel-catalyzed regioselective cross-electrophile ring opening reaction of sulfonyl-protected aziridines with trifluoromethyl-substituted alkenes as the gem-difluoroallylating agents, providing a new and efficient entry to prepare gem-difluorobishomoallylic sulfonamides. Moreover, the scaffold of 6-fluoro-1,2,3,4-tetrahydropyridine can be constructed starting from the ring opening products via NaH-mediated intramolecular defluorinative nucleophilic vinylic substitution.

Synthesis of Enantiomerically Enriched Protected 2-Amino-, 2,3-Diamino- and 2-Amino-3-Hydroxypropylphosphonates.

Simple and efficient strategies for the syntheses of enantiomerically enriched functionalized diethyl 2-amino-, 2,3-diamino- and 2-amino-3-hydroxypropylphosphonates have been developed starting from, respectively, N-protected (aziridin-2-yl)methylphosphonates, employing a regioselective aziridine ring-opening reaction with corresponding nucleophiles. Diethyl (R)- and (S)-2-(N-Boc-amino)propylphosphonates were obtained via direct regiospecific hydrogenolysis of the respective enantiomer of (R)- and (S)-N-Boc-(aziridin-2-yl)methylphosphonates. N-Boc-protected (R)- and (S)-2,3-diaminopropylphosphonates were synthesized from (R)- and (S)-N-Bn-(aziridin-2-yl)methylphosphonates via a regiospecific ring-opening reaction with neat trimethylsilyl azide and subsequent reduction of (R)- and (S)-2-(N-Boc-amino)-3-azidopropylphosphonates using triphenylphosphine. On the other hand, treatment of the corresponding (R)- and (S)-N-Bn-(aziridin-2-yl)methylphosphonates with glacial acetic acid led regiospecifically to the formation of (R)- and (S)-2-(N-Bn-amino)-3-acetoxypropylphosphonates.

Progress in Transition Metal-Catalyzed Asymmetric Ring-Opening Reactions of Epoxides and Aziridines

Progress in Transition Metal-Catalyzed Asymmetric Ring-Opening Reactions of Epoxides and Aziridines

Copper-Catalyzed Ring-Opening Reactions of Alkyl Aziridines with B2pin2: Experimental and Computational Studies.

The possibility to form new C–B bonds with aziridines using diboron derivatives continues to be a particularly challenging field in view of the direct preparation of functionalized β-aminoboronates, which are important compounds in drug discovery, being a bioisostere of β-aminoacids. We now report experimental and computational data that allows the individuation of the structural requisites and of reaction conditions necessary to open alkyl aziridines using bis(pinacolate)diboron (B2pin2) in a regioselective nucleophilic addition reaction under copper catalysis.

Ring Opening of Epoxides and Aziridines with Benzotriazoles Using Magnetically Retrievable Graphene Based (CoFe@rGO) Nanohybrid

AbstractReduced Graphene oxide (rGO) behaves as an excellent heterogeneous catalyst because of its remarkable characteristics such as large specific surface area and high thermal stability. In this regard, Graphene oxide was converted to magnetic nanohybrid (CoFe@rGO) and utilized as an efficient heterogeneous catalyst for the ring opening reactions and act as Lewis acid to promote the reaction. Developed a new facile, environmentally benign and green methodology for the synthesis of β‐hydroxytriazoles and β‐N‐tosylsulfonamidetriazoles derivatives via ring opening reaction of epoxides and aziridines respectively in the presence of CoFe@rGO nanohybrid as catalyst in good to excellent yields under solvent free reaction conditions. Catalyst was separated from the reaction mixture by an external magnet, recycled and reused up to six catalytic runs without significant loss of catalytic activity. Environmentally benign conditions, cheap starting materials, shorter reaction times, easy work‐up and purification of the products, high regioselectivity, high yields, recyclability and reusability of catalyst are the main advantages of our protocol.

Synthesis of Fingolimod Employing Regioselective Aziridine Ring-Opening Reaction as a Key Step

Synthesis of Fingolimod Employing Regioselective Aziridine Ring-Opening Reaction as a Key Step

Ring Opening of Epoxides and Aziridines with Benzotriazoles Using Magnetically Retrievable Graphene Based (CoFe@rGO) Nanohybrid

Reduced Graphene oxide (rGO) behaves as an excellent heterogeneous catalyst because of its remarkable characteristics such as large specific surface area and high thermal stability. In this regards, Graphene oxide was converted to magnetic nanohybrid (CoFe@rGO) and utilized as an efficient heterogeneous catalyst for the ring opening reactions and act as Lewis acid to promote the reaction. Developed a new facile, environmentally benign and green methodology for the synthesis of β-hydroxytriazoles and β- N -tosylsulfonamidetriazoles derivatives via ring opening reaction of epoxides and aziridines respectively in the presence of CoFe@rGO nanohybrid as catalyst in good to excellent yields under solvent free reaction conditions. Catalyst was separated from the reaction mixture by an external magnet, recycled and reused up to six catalytic runs without significant loss of catalytic activity. Environmentally benign conditions, cheap starting materials, shorter reaction times, easy work-up and purification of the products, high regioselectivity, high yields, recyclability and reusability of catalyst are the main advantages of our protocol.

Synthesis of Functionalized Novel α‐Amino‐β‐alkoxyphosphonates through Regioselective Ring Opening of Aziridine‐2‐phosphonates

AbstractAziridines are highly useful compounds as building blocks for the synthesis of important organic compounds. Amino acid synthesis by aziridine ring opening reaction is a good example to the use of aziridines. Although this reaction is studied by many groups, the synthesis of amino phosphonic acids is less explored. In this study, we have carried out the ring opening reaction of aziridinyl phosphonates with a variety of alcohols including the more functional propargylic and allylic alcohols. These reactions provided functionalized α‐amino‐β‐alkoxyphosphonates in 40–91 % yield.

Synthesis of 2-Aminophosphates via SN2-Type Ring Openings of Aziridines with Organophosphoric Acids.

The synthesis of 2-aminophosphates is achieved by a SN2-type ring opening reaction of various N-protected or free aziridines with phosphoric acids in a regiospecific and/or enantiospecific way. A one-pot, two-step procedure is also developed enabling direct access to 2-aminophosphates from olefins without isolation of the aziridine intermediates.

Nucleophilic ring opening reactions of aziridines.

Aziridine ring opening reactions have gained tremendous importance in the synthesis of nitrogen containing biologically active molecules. During recent years, a great effort has been put forward by scientists toward unique bond construction methodologies via ring opening of aziridines. In this regard, a wide range of chiral metal- and organo-catalyzed desymmetrization reactions of aziridines have been reported with carbon, sulfur, oxygen, nitrogen, halogen, and other nucleophiles. In this review, an outline of methodologies adopted by a number of scientists during 2013-2017 for aziridine ring opening reactions as well as their synthetic applications is described.

Substituent Effects in Regio- and Stereoselective Ring-Opening Reaction of Aziridines with Et3N·3HF for β-Fluoroamine Synthesis

Substituent Effects in Regio- and Stereoselective Ring-Opening Reaction of Aziridines with Et3N·3HF for β-Fluoroamine Synthesis

An easy one-step procedure for the synthesis of novel β-functionalised tellurides

Novel β-hydroxy-,β-amino- and β-mercapto- dialkyl- and phenyl-alkyl tellurides have been achieved through regioselective ring opening reactions of oxiranes, aziridines and thiiranes with different Te-nucleophiles, including tellurosilanes. Tellurium-125 NMR chemical shifts of selected compounds have been measured.

Research Progress in the Ring-Opening Reactions of Aziridines by Carbon Nucleophiles

Research Progress in the Ring-Opening Reactions of Aziridines by Carbon Nucleophiles

Enantioselective Oxidative Ring-Opening Reaction of Aziridines with α-Nitroesters Using Cinchona Alkaloid Amide/Nickel(II) Catalysts

The enantioselective oxidative ring-opening reaction of aziridines with α-nitroacetates has been developed. Good yields and enantioselectivity were observed for the reaction of various aziridines using a novel cinchona alkaloid amide/NiBr2 catalyst. Both enantiomers of products could be obtained by using pseudoenantiomeric chiral catalysts. This process offers an efficient route for the synthesis of α-aminoketones.

Ring-Opening Reactions of the N-4-Nosyl Hough-Richardson Aziridine with Nitrogen Nucleophiles.

Dinosylated α-d-glucopyranoside was directly transformed into α-d-altropyranosides via in situ formed N-4-nosyl Hough-Richardson aziridine with nitrogen nucleophiles under mild conditions in fair to excellent yields. The scope of the aziridine ring-opening reaction was substantially broadened contrary to the conventional methods introducing solely the azide anion at high temperatures. If necessary, the N-4-nosyl Hough-Richardson aziridine can be isolated by filtration in a very good yield and high purity.

NON-ACTIVATED AZIRIDINES AS BUILDING BLOCKS FOR THE SYNTHESIS OF AZA-HETEROCYCLES

This microreview deals with ring opening reactions of non-activated aziridines and their applications in heterocycle synthesis. Only recent methods published in the last five years are discussed.

ChemInform Abstract: Exploiting the σ‐Phylic Properties of Cationic Gold(I) Catalysts in the Ring Opening Reactions of Aziridines with Indoles.

AbstractStarting from 2‐substituted indoles the title transformation gives rise to a large range of tryptamine derivatives.