Azido Esters Research Articles

Asymmertic Synthesis of β‐Azido Esters through a Combination of Aldol and Mitsunobu Reactions

AbstractThis method offers several advantages over traditional methods for the asymmetric synthesis of β‐azido esters. First, the use of N‐acetyl camphorsultam allows for excellent stereoselectivity in the aldol reaction, which is crucial for the subsequent Mitsunobu reaction. Second, the use of trimethylsilyl azide (TMSN3) instead of hydrazoic acid (HN3) eliminates the need for handling a highly toxic and explosive reagent, making the process safer and easier to carry out. Third, the use of basic conditions for the Mitsunobu reaction allows for the reaction to proceed efficiently without the formation of the undesired silyl ethers.

Rheological studies of energetic binder-plasticizer blends

ABSTRACT Two azido ester plasticizers, bis(1,3-diazido prop-2-yl) malonate and bis(1,3-diazido prop-2-yl) glutarate, were mixed with three different binders, Glycidyl azido polymer (GAP), 3,3-bis-(azidomethyl)oxetane-tetrahydrofuran (BAMO-THF or BT) and 3- nitratomethyl-3-methyl oxetane or Poly NIMMO (PLN) in the ratio of 20:80 (w/w) to study their rheological properties. The addition of plasticizer has reduced the viscosity of three polymer blends, which improved the flow behaviour to an acceptable range. The change in activation energies of polymer blends is also calculated. For all the combination of blends, the rate of change in shear stress and linear range of strain with stress decreases after addition of plasticizers. Variation of viscosity with applied stress is unaffected initially and then increases significantly which limits the linear viscoelastic region (LVR) due to the dilution effect.

1,2,3‐Triazoles by Click Chemistry Using Azido Esters as a Precursor

AbstractThis paper describes synthesis and characterization of new di, tetra, and hexa‐1,2,3‐triazoles by Click chemistry using synthesized azido esters as one of the precursors. The synthesized triazoles were subjected to detailed characterizations by FTIR, 1H NMR, 13C‐NMR, and HRMS. Thermal stability was also performed by using DSC and TGA.

Synthesis and Characterization of New Azido Esters Derived from Malonic Acid

AbstractThree new α,α‐diazidated azido esters derived from malonic acid were synthesized and characterized with a method of diazidation under mild reaction conditions. They are energy‐rich, small, liquid molecules which contain up to six azido moieties. The three synthesized compounds were compared to already known azidated malonic acid esters regarding their density, thermal stability, calculated heat of formation and energetic properties. Further they were tested and classified for their sensitivities according to UN guidelines.

Synthesis and Properties of 3-Azido-2,2-bis(azidomethyl)propyl 2-Azidoacetate: A Potential Azido Ester Plasticizer.

This study reports the synthesis and characterization of a novel azido ester plasticizer, 3-azido-2,2-bis(azidomethyl)propyl 2-azidoacetate (ABAMPA), with good yield and high purity. The density, impact sensitivity, friction sensitivity, thermal decomposition temperature and glass transition temperature were determined to be 1.326 g ⋅ cm-3 , 16 J, 324 N, 235.9 °C and -50.4 °C, respectively. The plasticizing effect of ABAMPA on glycidyl azide polymer (GAP) was calculated by molecular dynamics, the solubility parameter difference value was 1.7(J ⋅ cm-3 )0.5 , and the glass transition temperature of GAP was reduced from -35 °C to -43 °C when the weight ratio of ABAMPA and GAP was 50 : 50. The new azido ester exhibits high energy, remarkable thermostability and good compatibility with GAP, which indicates that it would have potential application in explosive and propellant formulations.

Synthesis of EDTA core dendrimers through a consecutive esterification-CuAAC process

ABSTRACTA novel class of thermostable G0 and G1-dendrimers was synthesized from the coupling of both propargyl and azido esters derived from EDTA through copper catalyzed azide-alkyne cycloaddition. The branching and size in these compounds were controlled by a simple azide-alkyne group position change in the CuAAC reaction in conjunction with the use of 1,3-diazido-propan-2-ol as a polyfunctional compound.

A Fresh Look at the Staudinger Reaction on Azido Esters: Formation of 2H-1,2,3-Triazol-4-ols from α-Azido Esters Using Trialkyl Phosphines.

Phenyl esters of α-azido acids react with trialkylphosphines in THF/H2O to give 5-substituted 2H-1,2,3-triazol-4-ols in good to excellent yields. In contrast, their reaction with PPh3 in THF/H2O give the amino esters as the major product and no triazoles. Reaction between an α-azido phenyl ester and P(OEt)3 provided the corresponding phosphoramidate in excellent yield, but no triazole was formed.

Synthetic approach to novel azido esters and their utility as energetic plasticizers

A modular approach towards a series of novel di azido, tetra azido and hexa azido esters is introduced here.

Synthesis, characterization, thermal and computational studies of novel tetra-azido esters as energetic plasticizers

This paper describes the synthesis and characterization of two novel tetra-azido energetic plasticizers from readily available commercial sources possessing good thermal stability. Two new energetic azido esters named bis(1,3-diazido prop-2-yl)malonate (1) and bis(1,3-diazido prop-2-yl)glutarate (2) have been synthesized and characterized by IR, 1H NMR, 13C NMR, HRMS, thermal analysis, and compatibility tests. Both azido esters (1 and 2) show good thermal stability with decomposition temperatures of 233.5°C and 232.6°C. Their densities are measured to be 1.25g/cm3 and 1.27g/cm3, respectively. Glass transition temperature (Tg) of both compounds 1 and 2 is −69°C and −68°C and after addition with binder shows reduction in Tg of polymer-plasticizer blends as compared to Tg of polymer only with single decomposition temperature values which indicate the presence of single phase homogeneous system. Thermal decomposition kinetics of both compounds was determined by DSC, using non-isothermal Kissinger and Friedman differential isoconversional method. Density functional theory calculations on compounds 1 and 2 predict positive heats of formations.

Azidation of anomeric nitro sugars: application in the synthesis of spiroaminals as glycosidase inhibitors

6,5-Fused sugar-derived spiroaminals have been synthesized from the azido esters obtained via the nucleophilic substitution reactions of unstable Michael adducts derived from 1-nitro sugars. Most of the spiroaminals synthesized showed moderate but selective inhibitory activities toward some glycosidases.

Studies on Triple Base Gun Propellant Based on Two Energetic Azido Esters

Triple base propellant is the workhorse propellant because it possesses several advantages like reduced flash, flame temperature, and erosion of the barrel as compared to double and single base propellant. Hence, efforts are going on worldwide to increase its performance by increasing its energy using energetic plasticizers and binders. In the present article, nonenergetic plasticizer dibutyl phthalate (DBP) is replaced by two energetic azido ester plasticizers, tris(azido acetoxy methyl) propane (TAAMP) and bis(azido acetoxy) bis(azido methyl) propane (BABAMP), in triple base composition and their different properties are studied. Experimental closed vessel (CV) results (loading density 0.2 g/cm3) clearly indicate that the triple base composition with 2% DBP has force constant 1018 J/g, which is increased to 1026 and 1030 J/g on replacement of DBP by 1 and 2% TAAMP, respectively. Mechanical properties of propellant compositions containing 1 and 2% TAAMP (compression strength 279 and 291 kgf/cm2, percentage compression 11.2 and 10.5, respectively) are also better than those of composition containing DBP (compression strength 275 kgf/cm2 and 10.3% compression). Similarly, 1 and 2% replacement of DBP by BABAMP shows further rise in energy (1032 J/g, 1038 J/g respectively) than that of compositions containing 1 and 2% TAAMP. These two compositions also exhibit better mechanical properties (compression strength 311.2 and 312.3 kgf/cm2, % compression 11.0 and 10.5, respectively) than compositions containing 1 and 2% TAAMP. The differential thermal analysis (DTA) results brought out the fact that the compositions containing energetic plasticizers revealed maximum decomposition temperature in the range of 172–174°C which is close to DBP plasticized triple base gun propellants (174°C). The energetic plasticized propellant compositions of both (TAAMP and BABAMP) showed sensitivity data in the range of (H50 19 to 22 cm, F of I 25 to 29 and friction insensitivity 19.2 kg) acceptable limit for gun propellant.

Synthesis and Characterization of Two Potential Energetic Azido Esters

AbstractTwo new energetic azido esters named 1,3‐bis(azidoacetoxy)‐2‐azidoacetoxymethyl‐2‐ethylpropane (I) and 1,3‐bis(azidoacetoxy)‐2,2‐bis(azidomethyl)propane (II), have been synthesized and characterized by IR, NMR and Elemental Analysis. Thermal studies revealed that azido esters I and II are stable up to 180 °C and their glass transition temperatures are −47 °C and −52 °C, respectively.

Dendtritic Azido Ester: A Potential Energetic Additive for High Energy Material (HEM) Formulations

A second-generation [G-2] terminally azido functionalized dendritic ester has been synthesized from a commercially available dendritic polyol BOLTORN® H20. Structural features were confirmed by IR, 1H NMR, and elemental analysis. The differential scanning calorimetry (DSC) analysis shows an acceptable thermal stability for practical applications in high energy material formulations.

Synthesis of 4-aminomethyl-tetrahydrofuran-2-carboxylates with 2,4- cis and 2,4- trans relationships

Templated tetrahydrofuran-based γ-azido esters were prepared with the C-2 and C-4 functionalities in cis and trans relative configurations. This was achieved by ring contraction of the suitably protected 2- O-triflates of pentono-1,5-lactones ( d-ribose and l-arabinose) with subsequent introduction of the azide via the 4- O-triflate. Access to a corresponding β-azido ester was achieved in good yield. Little elimination product was observed by introduction of the azide via the 3- O-triflate. These azido esters are scaffolds, which may be predisposed to adopt secondary structural motifs, for example, for use as peptidomimetics; they may also be utilised for the preparation of stereodiverse compound libraries.

Isopropyl 2,5-anhydro-6-azido-3,6-dideoxy-D-xylo-hexonate

Determination of the crystal structure of the title isopropyl azido ester, C9H15N3O4, confirmed its relative stereochemistry and validated further work on the use of a derived sugar amino acid (SAA) as a peptidomimetic.

The Synthesis of Carbohydrate α‐Amino Acids Utilizing the Corey—Link Reaction.

AbstractFor Abstract see ChemInform Abstract in Full Text.

The Synthesis of Carbohydrate α-Amino Acids Utilizing the Corey - Link Reaction

Various carbohydrate ketones (uloses) have been treated with chloroform under strongly basic conditions to yield trichloromethyl tertiary alcohols. These alcohols, when subjected to the conditions of the modified Corey–Link reaction (sodium azide and 1,8-diazabicyclo[5.4.0]undec-7-ene in methanol), generally gave the expected azido ester with complete stereocontrol. Subsequent transformations on these azido esters provided amino esters, azido acids, and, in one case, the amino acid. A similar sequence applied to a protected d-glucono-1,5-lactone was only partly successful. Single-crystal X-ray structures are reported for 1,2:5,6-di-O-isopropylidene-3-C-trichloromethyl-α-d-allose, (3S)-3-C-azido-3-C-carboxy-3-deoxy-1,2:5,6-di-O-isopropylidene-α-d-ribo-hexose, 1,2:5,6-di-O-cyclohexylidene-3-C-trichloromethyl-α-d-gulose, (3S)-3-C-amino-1,2:5,6-di-O-cyclohexylidene-3-deoxy-3-C-methoxycarbonyl-α-d-xylo-hexose, methyl 2-O-benzyl-4,6-O-benzylidene-3-C-trichloromethyl-α-d-alloside, methyl (2S)-2-C-azido-3-O-benzyl-4,6-O-benzylidene-2-deoxy-2-C-methoxycarbonyl-α-d-arabino-hexoside, methyl 2,3-di-O-benzyl-6-deoxy-4-C-trichloromethyl-β-d-galactoside, 3,4,5,7-tetra-O-benzyl-1,1,1-trichloro-1-deoxy-α-d-gluco-hept-2-ulose, and 5-O-benzyl-1,2-O-isopropylidene-3-C-trichloromethyl-α-d-ribose.

Synthesis of Sugar Azido or Amino Esters and Their Use as Building Blocks for the Preparation of Saccharide Nucleosides.

Several sugar azido or amino esters bearing an α- or a β-C-D-glucopyranosyl backbone have been prepared by TMSOTf/Ac2O-mediated α-C-glycosylation with concurrent selective removal of the primary benzyl group or selective acetolysis of the primary benzyl group of β-C-glycoside as key steps. Such structures have been successfully used as scaffolds for the synthesis of novel saccharide nucleosides. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Stereoselective preparation of ceramide and its skeleton backbone modified analogues via cyclic thionocarbonate intermediates derived by catalytic asymmetric dihydroxylation of alpha,beta-unsaturated ester precursors.

A novel and efficient synthetic route to ceramide 1a and skeleton backbone modified ceramide analogues 1b,c is reported. The syntheses utilize osmium-catalyzed asymmetric dihydroxylation of (E)-alpha, beta-unsaturated ester 5a-c as the chiral induction step, with the desired configurations in the products 1a-c, 2a, and 13 being generated by regioselective azide substitution at the alpha position of alpha,beta-dihydroxyesters 6a-c via a cyclic thionocarbonate intermediate. Azido esters 10a-c are converted to the corresponding ceramides 1a-c by a sequence of azide reduction, N-acylation, ester reduction (NaBH(4)/LiBr), and Birch reduction of the triple bond (Li, EtNH(2)). These seven- to eight-step syntheses afford the target compounds 1a-c with excellent stereocontrol and in 30-42% overall yields. Furthermore, propargylic alpha-azido-beta-hydroxyester 10a is converted to D-erythro-sphingosine 2a via simultaneous reduction of the triple bond, azido, and ester functional groups with LiAlH(4), providing a highly concise and practical four-step synthesis of this key naturally occurring sphingolipid. The L-erythro stereoisomers are also available in high enantiomeric purity by the method described herein.

Synthesis of Conformationally Constrained Spirohydantoins with a Dibenzo[a,d]heptadiene Ring

Conformationally constrained dibenzo[a,d]cycloheptadiene-based spirohydantoins were prepared from dibenzosuberone via the transformation of the α-hydroxy ester to the azido ester, followed by its reduction to the amino ester, and cyclization of the carbomethoxy N,N′-asymmetric ureas, derived from the amino ester with triphosgene and a variety of amines. A novel ring expansion reaction was also observed in the process.