Hydrolysis of epoxides and aziridines catalyzed by polymer-supported quarternary ammonium bisulfate

Macroporous resin （D201）-supported quartemary ammonium bisulfate （D201-HSO4） was prepared and effectively used in catalyzing the hydrolysis of epoxides or aziridines under mild and non-metal conditions to give the corresponding 1,2-diols and β-amino alcohols in high yields. The catalyst was facilely prepared and recyclable.

Facile Synthesis of Polyisothioureas via Alternating Copolymerization of Aziridines and Isothiocayanates

Isothiourea is an important class of sulfur-containing molecules showing unique catalytic and biological activities. As such,polyisothiourea is envisioned to be an interesting type of polymer that potentially exhibits a number of interesting properties. However, there is no access to synthesizing well-defined polyisothiourea, and currently isothiourea-containing polymers are mainly prepared by immobilizing onto other polymer's side chain. Herein, we report the first facile synthesis of polyisothioureas via alternating copolymerization of aziridines and isothiocayanates. Mediated by the catalytic system of phosphazene superbases/alcohol, a broad scope of aziridines and isothiocayanates could be transformed into polyisothioureas with adjustable substitutions(11 examples). The structures of obtained polyisothioureas were fully characterized with ^(1)H-NMR, ^(13)C-NMR, and ^(1)H-^(13)C HMBC NMR. Moreover, the polyisothioureas show tunable thermal properties depending on substitutions on the isothiourea linkages. The novel structure of these polyisothioureas will enable a powerful platform for the discovery of nextgeneration functional plastics.

Oxidative Dehydrogenative [3+3] Annulation of Benzylhydrazines with Aziridines Leading to Tetrahydrotriazines

Oxidative dehydrogenative [3+3] annulation of benzylhydrazines with N-sulfonylaziridines is described.A series of complex tetrahydro-1,2,4-triazines were produced under mild reaction conditions.

Eco-friendly co-catalyst-free cycloaddition of CO_(2)and aziridines activated by a porous MOF catalyst

Cycloaddition of CO_(2) with aziridines is an important reaction to obtain high-value products.Porous MOFs can catalyze this reaction,but co-catalysts are still necessary to improve the catalytic performance.Such a reaction catalyzed by MOFs-based materials without co-catalyst has not been reported hitherto.Herein,a porous and stable three-dimensional(3D)framework{[Ni(DCTP)]·6.5DMF}_(n)(1)with a large Langmuir surface area of 3,789 m^(2)/g was synthesized,which displayed high I2 adsorption ability up to 731.0 mg/g and could release it reversibly.Additionally,it exhibited a high CO_(2) adsorption capacity of 104.0 cm^(3)/g at 273 K.The investigation results revealed 1 could effectively catalyze the cycloaddition of CO_(2) and aziridines in the absence of additional co-catalyst,and it could maintain the catalytic activity after five cycles.Furthermore,1 also exhibited high catalytic activity for the gram-scale experiment.Importantly,it is the first MOF material as a heterogeneous catalyst for the conversion of CO_(2) and aziridines without co-catalyst.

Tri-n-butylphosphane catalyzed ring opening of aziridines with secondary amines

Ring opening of aziridine with dialkyl amine took place readily in the presence of catalytic amounts of tri-n-butylphosphane （10 mol%） in the mixture of CH3CN/H20 （10：1）, giving corresponding vicinal diamines in mediate to high yields （58-95%） with good regioselectivitie, while aromatic secondary amine could not react under the same conditions. Tri-n-butylphosphane exhibited different catalytic selectivity to amines from Lewis acid catalysts.

An Improved Protocol for Regioselective Ring-Opening of Sulfonyl Aziridines with Iodine Promoted by PPh3

A new route to synthesize β-iodo amines from sulfonyl aziridines and iodine was developed in the presence of PPh3. This ring-opening reaction was an efficient and simple process to give fl-iodo amines in excellent yields with high chemoselectivity.

Ring Opening of N-Sulfonyl Aziridines by Amines in Silica-Water

Ring opening reactions of N-sulfonyl aziridines by primary and secondary amines in silica gel(SG)-water system were achieved,which provided a mild,practical and environmentally benign method to synthesize mono-and bis-sulfonyl substituted amines.When primary and secondary amines were used in excess,they reacted with N-sulfonyl aziridines smoothly at room temperature,mainly affording 1∶1 ring opening products.Reactions of primary amines with 2 equiv.of aziridines produced 2∶1 ring opening products.Some 1∶1 products can be cyclized with CS2 to synthesize N-sulfonyl cyclothioureas also in water.

Sulfanion-initiated open-vessel anionic ring-opening polymerization of N-sulfonyl aziridines

Anionic ring-opening polymerization(AROP)of N-sulfonyl aziridines is an important synthetic route to linear polyethyleneimine(PEI)and its derivatives.In most cases,inert atmosphere and dry solvent were needed because of the oxygen-and water-sensitive initiators/catalysts used.Therefore,the AROP of N-sulfonyl aziridines that can be entirely operated in air atmosphere is still a challenging task.Herein,we report a series of sulfanions,including xanthates,dithiocarbamates,dithiobenzoates,thioacetates,and thiolates,as the initiators for the AROP of N-sulfonyl aziridines.Due to their good stability,openvessel polymerization was achieved with high livingness,affording a range of well-definedα-,ω-telechelic poly(N-sulfonyl aziridine)homopolymers and block copolymers with narrow dispersities and tunable molecular weights.Theα-end group of these polyaziridines was readily converted to thiol group,which enabled further post-polymerization functionalization with benzyl acrylate and poly(ethylene glycol)via thiol-ene click chemistry.The establishment of open-vessel sulfanion-initiated AROP of N-sulfonyl aziridines thus lays a solid foundation for the bulk preparation and application of poly(N-sulfonyl aziridine)s and PEI derivatives.

Mild,convenient and efficient synthesis of novel 2,2-dichloro-1,3-diarylaziridines from Schiff bases by phase transfer CTAB catalysis under low concentration alkaline conditions

A mild and efficient method for preparation of novel 2,2-dichloro-1,3-diarylaziridines from Schiff base compounds in the presence of Ar-cetyl-N,N,N-trimethyl ammonium bromide（CTAB） as phase transfer catalyst has been described.The reaction is dramatically enhanced in the presence of quaternary ammonium salt.The corresponding products have been obtained in excellent yields,high purity and short reaction times.

Tri-n-butylphosphine Mediated Ring-Opening Reactions of Aziridines or Epoxides with Diphenyl Diselenide

Aziridines and epoxides were reacted with diphenyl diselenide in the presence of a stoichiometric amount of （n-Bu）3P, respectively, giving β-amino- or β-hydroxy selenides in moderate to excellent yields under mild conditions. In the reactions the （n-Bu）3P might act as a reductant though it was a nucleophilic catalyst in other similar ring-opening reactions.

Fe(OTf)_(3) Catalyzed Annulation of 2,3-Disubstituted Indoles with Aziridines

A Fe(OTf)_(3) catalyzed[3+2]annulation reaction between 2,3-disubstituted indoles and N-Ts aziridines is described herein.A series of hexahydropyrrolo[3,4-b]indole derivatives bearing two consecutive quaternary carboncenters can be generated efficiently.The reaction features cheap catalyst,mild conditions and operational simplicity.

Diastereoselective synthesis of functionalized tetrahydro-γ-carbolines via a[3+3] cycloaddition of 2,2’-diester aziridines with β-(indol-2-yl)-α,β-unsaturated ketones

A Sc(OTf)3-catalyzed[3+3]cycloaddition of 2,2’-diester aziridines withβ-(indol-2-yl)-α,β-unsaturated ketones was developed,affording polysubstituted tetrahydro-y-carbolines in single diastereoisomers in good to excellent yields.

Synthesis of Substituted Aziridine from (1S,2S)-2-Amino-1- (4-Nitrophenyl)- 1,3-Propanediol

(2S, 3R)-2-acetooxymethanyl-3-(P-nitrophenyl)-N-tosylaziridine 5 was synthesized from (1S, 2S)-2-amino-1-(4-nitrophenyl)-1, 3-propanediol 1 in four steps with a 24.8% overall yield. This reaction is stereospecific and occurs an expectable configuration inversion at α-carbon atom of benzyl group. The structure of substituted aziridine was determined on FT-IR, NMR, MS and so on.

Synthesis of Quinolone Analogues: 7-[2-Aminomethylaziridin-l-yl]-quinolones

New quinolone derivatives of 7-[2-aminomethylaziridin-l-yl]quinolone-3-carboxylic acids were synthesized. The structures of these compounds were characterized by IH NMR and HRESI-MS.

Synthesis and characterization of polyfunctional aziridine/polyester microcapsules by multiple emulsion-solvent evaporation method

Polyfunctional aziridine/polyester microcapsules as control-release waterborne cross-linker were synthesized by multiple emulsion-solvent evaporation method. The results show that,a lower surface free energy with shell polyester is more favourable for the formation of microcapsules. Full encapsulating microcapsules are synthesized with the polyester with a surface free energy of 34.5 mJ/m2. Shell-to-core feeding mass ratio has a significant influence on the morphology and core content of the resulting microcapsules. Well defined spherical microcapsules with uniform shell thickness and core content at around 22% are produced at a shell-to-core mass ratio of 1:1. When 2.5% of colloid stabilizer is used,hollow spherical microcapsules are obtained. A high solvent evaporation rate results in wrinkling and porosity of the microcapsules,and an evaporation rate equivalent to solvent elimination in about 2 h provides a uniform rate of surface hardening. The characterization of the microcapsules by SEM and FTIR demonstrates that polyfunctional aziridine is encapsulated at the centre of the microcapsule. The microcapsules synthesized can be broken at a high shear rate.

CURING KINETICS AND PROPERTIES OF ACRYLIC RESIN CURED WITH AZIRIDINE CROSSLINKER

A kind of aziridine crosslinkers was synthesized and used to crosslink acrylate copolymers. The crosslinking properties and curing kinetics of the resin were studied. It was found that with the increase of the content of crosslinker in the emulsion, the mechanical properties and solvent resistance of the resin will be apparently improved, but its glass transition temperature (T.) is very low. The lowest amount of crosslinker used in the acrylic resin emulsion is 0.25%. Curing kinetics studied by DSC show that this curing reaction occurs readily because the apparent activation energy of the reaction is low (65.1 kJ/mol). These results demonstrate that the aziridine crosslinker is indeed a low temperature crosslinking agent and can be used at room temperature.

Synthesis and Crystal Structure of Chiral 4-Hydroxy-4-butyrolactam Fused Aziridine

A novel compound of chiral 4-hydroxy-4-butyrolactam fused aziridine was synthesized via tandem nucleophilic displacement reaction under mild condition. Its structure was determined by IR, 1H NMR, elemental analysis and X-ray diffraction. The crystal of the new compound is of orthorhombic, space group P212121 with a = 6.4246（6）, b = 13.5081（13）, c = 18.6399（18） A, Mr = 278.39, Z = 4, V = 1617.6（3）A^3, Dc = 1.143 g/cm^3, p（MoKa） = 0.075 mm^-1, F（000） = 608, the final R = 0.0297 and wR = 0.0679.

Modification of Natural Rubber Latex by Graft Copolymerization of 2-Ethylhexyl Acrylate and Methacrylic Acid

Natural rubber(NR)grafted with 2-ethylhexyl acrylate(2-EHA)and methacrylic acid(MAA,collectively NR-g-PEHA/MAA)was synthesized by emulsion polymerization.Tetraethylenepentamine and cumene hydroperoxide were used as redox initiators.The successful grafting of 2-EHA and MAA onto NR was confirmed by Fourier transform infrared spectroscopy.The morphology of the NR latex particles was observed by transmission electron microscopy.The effects of reaction temperature,initiator dosage,feeding mode,and hard monomer content on the mechanical properties of the modified NR film were investigated.Grafted polymer chains were unevenly wrapped on the outside of NR particles,and smaller particles were more easily grafted.Crosslinking was characterized using a toluene swelling method.Thermal stability and glass transition temperature were examined by differential scanning calorimetry and thermogravimetric analysis.The results showed that the thermal stability of NR-g-PEHA/MAA had been improved,and the glass transition temperature(Tg)was unchanged.

The Influence of Aziridine on the Aging of Composite Solid Rocket Propellant

Aging of a solid composite propellant containing HTPB/AP/AL was performed in order to validate the conformance of the accelerated aging data to the Arrhenius law. The main objective of the work was to examine the influence of the aziridine bonding agents family on the propellant aging. Aging of the prepared propellant samples was conducted as follows: 1. Four samples, one free of bonding agents, and three containing aziridine based bonding agents MAPO,HX-752, MAT4 were aged at 65°C. 2. Another four samples based on HX-752, MAT4 with different curing agents were aged at 65°C. The measured mechanical properties of the free bonding agent propellant samples were very far from the specifications and this illustrates the importance of the bonding agents in both the preparation and the aging phases.The prepared bonding agent 'MAT4' gave remarkable improvements of the mechanical properties comparing with HX-752 and MAPO. The aziridine bonding agents family inhibited the rate of decomposition of the propellant during the aging periods and supported the propellant matrix against decomposition at the elevate temperatures. Using of HMDI as curing agent gave slight better mechanical properties to the IPDI.

Recent advances in transition-metal catalyzed nitrene transfer reactions with carbamates

Nitrene transfer reactions are powerful tools in synthetic organic chemistry.In recent years,transitionmetal catalyzed nitrene transfer reactions with carbamates as the nitrene precursors have been widely pursued.Such species undergoes facile C-H amination,aziridination,and bifunctionalization of alkenes under the catalysis of different transition metals including Rh,Fe,Ru and others,enabling the efficient construction of various nitrogen-containing molecules.In this review,the recent developments in nitrene transfer reactions with carbamates via N-O bond cleavage were introduced based on different types of reaction,and the key mechanistic information and synthetic applications of the methodologies were discussed.