•The regioselectivity is controlled by stepwise cis-cycloaddition pathway.•The enantioselectivities are sensitive to the temperature of the reaction.•The stereoselectivities of 1,3-DCA reaction are sensitive to the nature of amino acids chelated to the transition metal.Cobalt II(l-phenylalanine)2 was used effectively for the first time in a catalytic asymmetric 1,3-dipolar cycloaddition of azomethine ylides with 2-arylidenindane-1,3-diones, affording a series of novel spiropyrrolidine derivatives with good to high yields (up to 90%), excellent diastereoselectivities (only exo’-3 were detected), and good enantioselectivities (up to 87% ee).Download high-res image (98KB)Download full-size image

Cinchonine was effectively used in an AgOAc-catalysed asymmetric 1,3-dipolar cycloaddition of azomethine ylides with 2,6-bis(arylmethylidene) cyclohexanones, affording spiropyrrolidine derivatives with excellent yields (up to 99%), diastereoselectivities (up to 96:04 dr), and enantioselectivities (up to 99% ee).Download high-res image (84KB)Download full-size image

•The regioselectivity is controlled by stepwise cis-cycloaddition pathway.•The diastereoselectivities are sensitive to the nature of copper salt.•The stereoselectivities of 1,3-DCA reaction are sensitive to the structure of oxazoline ring.A ferrocene-derived P,N-heterodonor ligand was effectively used in a Cu(OAc)2·H2O-catalysed asymmetric 1,3-dipolar cycloaddition of azomethine ylides with maleate derivatives, affording cycloadducts with high yields (up to 96%), diastereoselectivities (>99 dr), and enantioselectivities (up to 99% ee).Download high-res image (60KB)Download full-size image

The synthesis of diastereo- and enantiopure heterocyclic molecules via catalytic asymmetric 1,3-dipolar cycloaddition reaction between azomethine ylides, generated in situ from α-amino acid-derived iminoesters and dipolarophiles is considered one of the most powerful and versatile techniques. In this review, we make a detailed overview of the latest developments in this area since 2014 and highlight the recent improvements in the structural scope of dipolarophiles, azomethine ylide precursors, and chiral ligands.Download high-res image (74KB)Download full-size image

To reach the long-term, strongly desired goal of high energy density materials (HEDM), a novel N-bridged structure of N-(3,5-dinitro-1H-pyrazol-4-yl)-1H-tetrazol-5-amine, and its selected nitrogen-rich energetic salts are designed and synthesized. All compounds are fully characterized by 1H and 13C NMR (in some cases, 15N NMR) spectroscopy, IR spectroscopy, HRMS and elemental analysis. Of these, salts 6·H2O and 10 are further confirmed by single-crystal X-ray diffraction. The densities of these compounds ranged from 1.67 to 1.86 g cm−3. All energetic salts exhibit excellent thermal stabilities with decomposition temperatures ranging from 216 to 299 °C and all are insensitive to impact. Decomposition of these thermally stable compounds (salts 2, 3, and 4) occurs at 299, 296, and 290 °C, respectively. Theoretical performance calculations (Gaussian 03 and EXPLO5 v6.01) provide detonation pressures and velocities for the energetic salts in the ranges 25.9–37.4 GPa and 8264–9364 m s−1, respectively; six of the energetic compounds have detonation velocities >9000 m s−1. Notably, the unique overall performance of salt 4 thus exceeds those of commonly used explosives such as HMX. Thus, due to its insensitivity (IS > 40 J, FS = 360 N), fairly high detonation velocity (vD = 9364 m s−1), exceptional thermal stability (Td = 290 °C), and high nitrogen content (N = 56.4%), salt 4 is a prospective candidate for a new class of insensitive, highly energetic explosives.

The combination of superior energetic structural fragments is a feasible route to design new energetic materials. In this work, selected metal and nitrogen-rich salts based on 3,4-dinitro-1-(1H-tetrazol-5-yl)-1H-pyrazol-5-amine (HANTP) are prepared and characterized by 1H/13C NMR, IR spectroscopy, and elemental analysis. The crystal structures of neutral HANTP (2), and its potassium (4), sodium (5), ammonium (6), and guanidinium (9) salts are determined by single-crystal X-ray diffraction, and their properties (density, thermal stability, and sensitivity towards impact and friction) are investigated. The detonation properties are evaluated by the EXPLO5 (v6.01) program using the measured density and calculated heat of formation (Gaussian 03). All compounds exhibit thermal stabilities with decomposition temperatures ranging from 171 to 270 °C, high densities (1.61–2.92 g cm−3), and high positive heats of formation (630.4–1275.2 kJ mol−1). The inorganic salts (4 and 5) assume particular structures (two-dimensional and one-dimensional metal–organic frameworks, respectively). Suitable impact and friction sensitivities and being free of toxic metals place these compounds within the green primary explosives group and several of the new organic salts exhibit detonation and other properties that compete with, or exceed the performance of those of HMX.

Twelve salts of 3-nitro-1,2,4-triazol-5-one (NTO) (ammonium, hydrazinium, guanidinium, aminoguanidinium, diaminoguanidinium, triaminoguanidinium, N-carbamoylguanidinium, semicarbazidium, 1,5-diamino-1,2,4-tetrazolium, 3,4,5- triamino-1,2,4-triazolium, 3,6,7-triamino-7H-[1, 2, 4]triazolo[5,1-c][1,2,4]triazol-2- ium, and 4,4′,5,5′-tetraamino-3,3′-bi-1,2,4-triazolium) were synthesized. The new salts were fully characterized by 1H and 13C NMR spectroscopy, infrared spectroscopy, and elemental analysis. The crystal structures of salts 10 and 11 were determined by single-crystal X-ray diffraction. All energetic salts except salt 6 exhibit excellent thermal stabilities with decomposition temperatures ranging from 203 to 270 °C. The densities of salts ranged from 1.65 to 1.88 g cm−1 as measured by a gas pycnometer. Theoretical performance calculations (Gaussian 03 and EXPLO5 v6.01) yielded detonation pressures and detonation velocities for the energetic salts, ranging from 24.4 to 38.1 GPa and 8136 to 9575 m s−1, respectively. In particular, salt 2 has an outstanding detonation performance (Pcj = 38.1 GPa, vD = 9575 m s−1) with a satisfactory acidity compared to that of NTO (pKa = 5.63 versus pKa = 2.37). Furthermore, the particles of salt 2 form two-dimensional blades of submicron size, as determined by scanning electron microscopy analysis. Meanwhile, salt 2 was compatible with TNAZ, TATB, TKX-50, Al, NH4ClO4, CL-20, TNT, and F2603 fluororubber, as determined by differential scanning calorimetry or vacuum stability tests.

The unique and facile synthesis of 7-nitro-4-oxo-4,8-dihydro-[1,2,4]triazolo[5,1-d][1,2,3,5]tetrazine 2-oxide (HBCM) and a proposed mechanism for its formation are described. The hygroscopicity of HBCM was overcome by transforming it into salts. The energetic salts of HBCM were characterized by 1H and 13C nuclear magnetic resonance spectroscopy, infrared spectroscopy, differential scanning calorimetry (DSC) and elemental analysis. The crystal structures of the sodium and guanidinium salts were determined by single-crystal X-ray diffraction. The densities of the salts ranged from 1.77 to 1.97 g cm−3. Most of the energetic salts decomposed above 230 °C and tended to be insensitive to impact, friction and electrostatic discharge. Theoretical performance calculations (Gaussian 03 and EXPLO5) for the energetic salts provide detonation pressures and velocities within the ranges of 25.2 to 39.5 GPa and 7856 to 9069 m s−1, respectively. The hydroxylammonium salt showed high density (1.97 g cm−3), acceptable decomposition temperature (Td = 197 °C), low sensitivities, and excellent detonation velocity (9069 m s−1) and pressure (39.5 GPa), which suggests that it has the potential to be used as a high-energy-density material.

A new family of nitrogen-rich energetic salts based on 3-nitro-1-(2H-tetrazol-5-yl)-1H-1,2,4-triazol-5-amine (HANTT) were synthesized and characterized by 1H and 13C nuclear magnetic resonance, infrared spectroscopy and elemental analysis. The crystal structures of neutral HANTT (2), its guanidinium salt (3), and 1,5-diamino-tetrazolium salt (9) were determined by single-crystal X-ray diffraction. All energetic salts exhibit excellent thermal stabilities with decomposition temperatures ranging within 264–321 °C and are insensitive to impact, friction and electrostatic discharge. The densities of salts 3–10 ranged from 1.65 g cm−3 to 1.81 g cm−3. Theoretical performance calculations (Gaussian 03 and EXPLO5) provided detonation pressures and velocities for the energetic salts within the ranges of 22.6–32.6 GPa and 7742–8779 m s−1, respectively, making them competitive energetic materials.

•New AT1 blockers with a chiral center were synthesized.•Eight compounds were potent in the AT1 antagonism in vitro.•One compound was of excellent efficacy in antihypertension and low toxicity.•The best molecule showed strong interactions with the AT1 model in docking study.Novel angiotensin II receptor type 1 (AT1) blockers bearing 6-substituted carbamoyl benzimidazoles with a chiral center were designed and synthesized as the first step to develop new antihypertensive agents and understand their pharmacodynamic and pharmacokinetic properties. The newly synthesized compounds were tested for their potential ability to displace [125I] Sar1 Ile8-Ang II, which was specifically bound to human AT1 receptor. Radioligand binding assays revealed nanomolar affinity in several compounds under study. The IC50 values of nine ligands were higher than those of Losartan. The screening of decreased blood pressure in spontaneous hypertensive rats displayed that compound 8S (IC50 = 5.0 nM) was equipotent with Losartan, whereas compounds 13R (IC50 = 7.3 nM), 14R (IC50 = 6.3 nM), and 14S (IC50 = 3.5 nM) were slightly ahead of Losartan, and the most significant activity was demonstrated by compound 8R (IC50 = 1.1 nM). Candidate 8R was identified for its excellent efficacy in antihypertension and fairly low toxicity based on plasma analyses, toxicology studies, and chronic oral tests. Finally, compound 8R exhibited strong and multiple interactions with target active sites of the theoretical AT1 receptor model in docking study.

Organometallic and organo-catalysts are cooperatively at work in the enantioselective synthesis of dibenzopyran derivatives; palladium/norbornene and a cinchona alkaloid base guarantee good yields and satisfactory enantioselectivities in a one-pot reaction.

Correction for ‘A novel enantioselective synthesis of 6H-dibenzopyran derivatives by combined palladium/norbornene and cinchona alkaloid catalysis’ by Di Xu et al., Org. Biomol. Chem., 2015, DOI: 10.1039/c4ob02551b.

Highly efficient and recyclable imidazolium-tagged bis(oxazolines), with an imidazolium tagged onto the 4,4′-position of the box, have been designed and prepared for the first time. They have been synthesized from dimethylmalonic acid and used as chiral ligands in the copper(II)-catalyzed classic asymmetric Henry reaction between aldehydes and nitromethane. A systematic analysis of the anions showed that the best ligand was one of a medium size; the catalyst achieved a high activity and enantioselectivity as well as good recyclability, i.e., product (R)-11k was attained at 94% ee in MeOH. Moreover, the catalyst was successfully recycled six times, without an obvious loss in activity or enantioselectivity. Finally, a theoretical mechanistic study was conducted to explain the origin of the enantioselectivity and how the size of anions affects the reaction.

By introducing the novel fragment [N-(1H-tetrazol-5-yl)-amide], a series of 4′-[(benzimidazol-1-yl)methyl]biphenyl-2-amides (1a–1w) was designed, synthesized and biologically evaluated. 1d, 1k and 1p showed potent antagonistic activities against the angiotensin II receptor (AT1) and the endothelin A receptor (ETA). The evaluation in spontaneous hypertensive rats indicated that the oral activity of compound 1p was more potent than Irbesartan. Structural biological studies of 1p revealed that strong interactions to the AT1 and ETA receptors were explicit and the tetrazol-5-ylamide could be an important moiety for the binding to the proteins.

A series of novel 4′-[(benzimidazol-1-yl)methyl]biphenyl-2-sulphonamides was designed, and their molecular model simulation fitting to a new HipHop 3D pharmacophore model was examined. Several compounds showed significantly high simulation fit values. The designed compounds were synthesised, 22 of which were biologically evaluated in vitro using the dual receptor binding assay. Compound 11 showed potent antagonistic activity against both angiotensin II AT1 and endothelin ETA receptors. Obtaining a highly active compound from a candidate set of only 22 compounds illustrates the power and utility of our pharmacophore model.

A series of imidazolium moiety tagged planar chiral ferrocenyl oxazoline phosphine (FimiOAXP) ligands were designed and synthesised. In connection with their usefulness as ligands for asymmetric 1,3-dipolar cycloadditions of azomethine ylides with nitroalkenes, the catalysts were prepared in situ by treatment of copper(I) perchlorate and FimiOAXP. In the presence of a weak base, the pyrrolidine analogues were obtained in satisfactory yields and with excellent enantioselectivities (up to 99% ee). Through the experimental and computational outcomes, ion effect between the imidazolium moiety and azomethine ylide proved to be an essential factor for the excellent enantioselectivity. Moreover, with the benefit of the imidazolium moiety, the asymmetric 1,3-dipolar cycloaddition underwent in DCM/ionic liquids combined solvent for the first time. Taking advantage of the occasion, the catalyst could be recycled and reused for at least five times.(R)-4-Hydroxymethyl-2-ferrocenyloxazolineC14H15FeNO2[α]D20 = +84.0 (c 0.05, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (R)(S)-4-(tert-Butyldimethylsilyloxy)methyl-2-ferrocenyloxazolineC20H29FeNO2Si[α]D20 = +24.1 (c 0.28, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (S)(S,Rp)-4-(tert-Butyldimethylsilyloxy)methyl-2-[(2-diphenylphosphino)ferrocenyl]oxazolineC32H38FeNO2PSi[α]D20 = +82.4 (c 0.24, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (S,Rp)(R,Rp)-4-Hydroxymethyl-2-[(2-diphenylphosphino)ferrocenyl]oxazolineC26H24FeNO2P[α]D20 = +246.0 (c 0.12, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (R,Rp)(R,Rp)-1-[2-[2-(Diphenylphosphino)ferrocenyl]oxazolinyl]methyl-2,3-dimethylimidazole, trifluoromethyl sulfonateC32H31F3FeN3O4PS[α]D20 = +261.6 (c 0.17, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (R,Rp)(R,Rp)-1-[2-[2-(Diphenylphosphino)ferrocenyl]oxazolinyl]methyl-2,3-dimethylimidazole, hexafluorophosphateC31H31F6FeN3OP2[α]D20 = +296.1 (c 0.10, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (R,Rp)(R,Rp)-1-[2-[2-(Diphenylphosphino)ferrocenyl]oxazolinyl]methyl-2,3-dimethylimidazole, tetrafluoroborateC31H31BF4FeN3OP[α]D20 = +326.0 (c 0.10, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (R,Rp)(R,Rp)-1-[2-[2-(Diphenylphosphino)ferrocenyl]oxazolinyl]methyl-2,3-dimethylimidazole, iodideC31H31FeIN3OP[α]D20 = +239.3 (c 0.22, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (R,Rp)(R,Rp)-1-[2-[2-(Diphenylphosphino)ferrocenyl]oxazolinyl]methyl-2,3-dimethylimidazole, perchlorateC31H31ClFeIN3O5P[α]D20 = +298.1 (c 0.11, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (R,Rp)

New polynitro-substituted bispyrazoles were synthesised and fully characterised in this study. Ammonium 4-(4′-amino-3′,5′-dinitro-1′-pyrazol)-3,5-dinitropyrazole (3), 4-(4′-amino-3′,5′-dinitro-1′-pyrazol)-1-amino-3,5-initropyrazole (6), diaminoguanidinium 4-(4′-amino-3′,5′-dinitro-1′-pyrazol)-3,5-dinitropyrazole (9), and 3,4,5-triamino-1,2,4-triazolium 4-(4′-amino-3′,5′-dinitro-1′-pyrazol)-3,5-dinitropyrazole (12) were further confirmed using single-crystal X-ray diffraction. The compounds exhibited excellent thermal stabilities, insensitivities and high detonation performance. The measured LC50 of the compounds suggested that their toxicities were lower than that of TNT and that for compound 3 even lower than that of TATB. Compound 5 demonstrates unprecedented overall performance: higher detonation velocity (VD = 8760–8981 m s−1), detonation heat (Qv = 7551 kJ kg−1) and explosive power (A = 1712 kJ g−1) than RDX, a decomposition temperature (Td = 297 °C) higher than that of HMX, and much lower toxicity (LC50 = 7 μg mL−1) than that of TNT, ranking it in a new generation of heat resistant, less sensitive and low environmental impact high energetic materials.

Energetic salts based on bis(N-dinitroethyl)aminofurazan were synthesised. All salts were fully characterised using 1H and 13C multinuclear NMR spectroscopy, infrared spectroscopy, elemental analysis, density analysis, and differential scanning calorimetry. These salts exhibited reasonable physical properties, such as high densities (1.72 g cm−3 to 1.94 g cm−3) and low solubilities in water. Based on the experimental densities, the detonation pressures and velocities of the energetic salts were calculated, ranging from 26.1 GPa to 39.4 GPa and 8055 m s−1 to 9388 m s−1, respectively. These value were higher than those of TNT and similar to those of RDX. The thermal stability and thermal kinetic parameters of the new energetic salts were also evaluated using Kissinger’s and Ozawa’s methods, coupled with DSC.

•Both 6-substituted aminocarbonyl and acylamino benzimidazole derivatives were designed and synthesized.•Most compounds exhibited nanomolar AT1 receptor binding affinity and high AT1 receptor selectivity over AT2 receptor.•Compounds 6f and 11g are orally active AT1 receptor antagonists.Both 6-substituted aminocarbonyl and acylamino benzimidazole derivatives were designed and synthesized as nonpeptidic angiotensin II AT1 receptor antagonists. Compounds 6f, 6g, 11e, 11f, 11g, and 12 showed nanomolar AT1 receptor binding affinity and high AT1 receptor selectivity over AT2 receptor in a preliminary pharmacological evaluation. Among them, the two most active compounds 6f (AT1 IC50 = 3 nM, AT2 IC50 > 10,000 nM, PA2 = 8.51) and 11g (AT1 IC50 = 0.1 nM, AT2 IC50 = 149 nM, PA2 = 8.43) exhibited good antagonistic activity in isolated rabbit aortic strip functional assay. In addition, they were orally active AT1 receptor antagonists in spontaneous hypertensive rats.

New energetic salts based on 1-nitramino-2,4-dinitroimidazole were successfully synthesized. The salts were fully characterized by 1H, 13C NMR and IR spectroscopy, differential scanning calorimetry (DSC), and elemental analyses. The salts were found to have good physical and detonation properties. The structure of guanidinium salt (3) was further confirmed by single-crystal X-ray diffraction. The densities of the energetic salts ranged between 1.70 and 1.93 g cm−3 as measured by a gas pycnometer. The detonation pressures and velocities calculated by the EXPLO5 code ranged within 29.3–40.5 GPa and 8370–9209 m s−1, respectively.

Energetic salts based on 4,4′-oxybis[3,3′-(1H-5-tetrazol)]furazan were readily synthesized and fully characterized by NMR (1H, 13C), IR spectroscopy, elemental analysis, and differential scanning calorimetry (DSC). Bis(guanidinium) (6), bis(aminoguanidinium) (7), bis(diaminoguanidinium) (8) salts and carbonic dihydrazidinium(HBTFOF)2 (13) were further confirmed by single-crystal X-ray diffraction. All the salts exhibit excellent thermal stabilities with decomposition temperatures over the range 212–289 °C. The densities of the energetic salts ranged between 1.64 and 1.86 g cm−3. The detonation pressures and velocities were calculated to be between 19.7 and 30.8 GPa and 7266–8624 m s−1, respectively. Impact sensitivities were found to be in the range 5–36 J. The relationship between salt structure and thermal stability was studied by NBO analysis for compounds 6, 7, and 8.

Novel super-highly energetic bis(2,2-dinitroethyl)nitramine-based salts exhibiting excellent physical and detonation properties, such as low solubility in common solvents, moderate thermal stabilities, high densities, high detonation pressures and detonation velocities, were synthesized and fully characterized. The densities of the energetic salts range between 1.77 and 2.02 g cm−3 as measured using a gas pycnometer. The detonation pressures and velocities as calculated by the EXPLO5 code are in the range 31.5–46.2 GPa and 8586–10004 m s−1, which make them competitive super-highly energetic materials.

A series of 6-substituted aminocarbonyl benzimidazole derivatives were designed and synthesized as nonpeptidic angiotensin II AT1 receptor antagonists. The preliminary pharmacological evaluation revealed nanomolar AT1 receptor binding affinity and good AT1 receptor selectivity over AT2 receptor for all compounds of the series, a potent antagonistic activity in isolated rabbit aortic strip functional assay for compounds 6b, 6d and 6i was also demonstrated. Furthermore, evaluation in spontaneous hypertensive rats and a preliminary toxicity evaluation showed that compound 6i is an orally active AT1 receptor antagonist with low toxicity.Highlights► 6-Substituted aminocarbonyl benzimidazole derivatives were designed and synthesised. ► Most compounds exhibited nanomolar AT1 receptor binding affinity. ► Compounds 6i were found to be the most potent compound. ► The toxicities of most compounds prepared appear to be as low as that of telmisartan.

Functional imidazolium ionic liquids have been developed as a new class of versatile catalysts. C2-symmetric imidazolium-tagged bis(oxazoline) ligands were prepared, and the anions of the ligands were altered. The catalysts based on the new ligands and Cu(OAc)2·H2O were applied in asymmetric Henry reactions between various aldehydes 3 and CH3NO24. The catalysts achieved a high level of enantioselectivity; product (R)-5n was attained at 94% ee in MeOH. Moreover, the catalyst could be recycled 6 times without an obvious loss of activity or enantioselectivity. In addition, a theoretical mechanistic study was conducted to explain the origin of the enantioselectivity.

A series of 6-substituted carbamoyl benzimidazoles were designed and synthesised as new nonpeptidic angiotensin II AT1 receptor antagonists. The preliminary pharmacological evaluation revealed a nanomolar AT1 receptor binding affinity for all compounds in the series, and a potent antagonistic activity in an isolated rabbit aortic strip functional assay for compounds 6f, 6g, 6h and 6k was also demonstrated. Furthermore, evaluation in spontaneous hypertensive rats and a preliminary toxicity evaluation showed that compound 6g is an orally active AT1 receptor antagonist with low toxicity.A series of 6-substituted carbamoyl benzimidazoles were designed and synthesised. The in vitro and in vivo evaluation results showed that compound 6g is an orally active AT1 receptor antagonist with low toxicity.

Functional imidazolium ionic liquids have been developed as a new class of versatile catalysts. C2-symmetric and unsymmetric imidazolium-tagged bis(oxazoline) ligands were prepared, and the anions of the ligands were altered by ion-exchange reactions. The catalysts based on the new ligands and Cu(OTf)2 were applied in asymmetric Diels–Alder reactions between N-acryloyl/N-crotonoyloxazolidinones 15 and 1,3-cyclohexandiene/cyclopentadiene 16 in different ionic liquids and in dichloromethane (DCM). The catalysts achieved a high level of activity and enantioselectivity, as well as good recyclability: cycloadduct (S)-17ab was attained at 98% conversion and 97% ee in [Bmim]NTf2. Moreover, the catalyst could be recycled 20 times without an obvious loss of activity or enantioselectivity. By comparison, we deduced that the C2 symmetry of the new ligands was crucial for obtaining high ee values. Toxicity studies of the ligands were performed for the first time.

A novel cyclodextrin (CD) derivative, mono-6-deoxy-benzimide-β-CD (MB-β-CD), in which a rigid substituent was linked to the narrow edge of the CD with a flexible H2C–N group, was successfully synthesized through the condensation of mono-6-deoxy-6-amino-β-cyclodextrin and benzaldehyde. To evaluate its enantioseparation abilities and investigate the role of the CD substituents and linkage in chiral recognition, MB-β-CD and mono-6-deoxyphenylimine-β-CD (MP-β-CD) with a rigid linkage were compared in the separation of 36 chiral compounds in a methanol/water mobile phase. The separation results showed that most of the analytes with rigid structures afforded better enantioresolutions on the MP-β-CD (with a rigid linkage) chiral stationary phase (CSP), while better enantioseparations for analytes with flexible structures and big steric hindrance were obtained on the MB-β-CD (with a flexible linkage) CSP. The former exhibited a specificity for the analyte structures, while the latter was more adaptable. Molecular dynamics simulations were performed to further understand the discrimination process and the function of the CD side arm.

A new type of ferrocenyl diphosphine–imine ligands that contains an ionic salt group has been prepared, and successfully applied to asymmetric C∗–O bond formation. In the Pd-catalyzed asymmetric allylic etherification of 1,3-diphenyl-2-propenyl acetate, high enantioselectivity was obtained (up to 91.0% ee). The potential of the catalysts to be recycled and reused has also been demonstrated.4-[(E)-[[(1S)-1-[(2R)-1′,2-Bis(diphenylphosphino)ferrocenyl]ethyl]imino]methyl]-N,N,N-trimethyl-benzenaminium, iodideC46H45FeIN2P2[α]D25=-336.9 (c 0.3, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (S,Rp)4-[(E)-[[(1R)-1-[(2R)-1′,2-Bis(diphenylphosphino)ferrocenyl]ethyl]imino]methyl]-N,N,N-trimethyl-benzenaminium, iodideC46H45FeIN2P2[α]D25=316.2 (c 0.3, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (R,Rp)4-[(E)-[[(1R)-1-[(2S)-1′,2-Bis(diphenylphosphino)ferrocenyl]ethyl]imino]methyl]-N,N,N-trimethyl-benzenaminium, hexafluorophosphateC46H45F6FeN2P3[α]D25=-340.4 (c 0.6, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (R,Sp)4-[(E)-[[(1R)-1-[(2S)-1′,2-Bis(diphenylphosphino)ferrocenyl]ethyl]imino]methyl]-N,N,N-trimethyl-benzenaminium, iodideC46H45FeIN2P2[α]D25=-337.3 (c 0.6, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (R,Sp)4-[(E)-[[(1R)-1-[(2S)-1′,2-Bis(diphenylphosphino)ferrocenyl]ethyl]imino]methyl]-N,N,N-trimethyl-benzenaminium, bromideC46H45FeBrN2P2[α]D25=-339.7 (c 0.6, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (R,Sp)4-[(E)-[[(1R)-1-[(2S)-1′,2-Bis(diphenylphosphino)ferrocenyl]ethyl]imino]methyl]-N,N,N-trimethyl-benzenaminium, trifluoromethanesulfonateC52H51FeN2O3P2S[α]D25=-362.3 (c 0.6, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (R,Sp)4-[(E)-[[(1R)-1-[(2S)-1′,2-Bis(diphenylphosphino)ferrocenyl]ethyl]imino]methyl]-N,N,N-trimethyl-benzenaminium, nitrateC46H45FeN3O3P2[α]D25=-341.5 (c 0.6, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (R,Sp)3-[(E)-[[(1R)-1-[(2S)-1′,2-Bis(diphenylphosphino)ferrocenyl]ethyl]imino]methyl]-N,N,N-trimethyl-benzenaminium, iodideC46H45FeIN2P2[α]D25=-332.76 (c 0.6, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (R,Sp)4-[(E)-[[(1R)-1-[(2S)-1′,2-Bis(diphenylphosphino)ferrocenyl]ethyl]imino]methyl]-N,N,N-trimethyl-benzenemethanaminium, iodideC47H47FeIN2P2[α]D25=-338.6 (c 0.6, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (R,Sp)3-[4-Formyl-[(E)-[(1R)-1-[(2S)-1′,2-bis(diphenylphosphino)ferrocenyl]ethyl]imino]methyl]-1-methyl-1H-imidazolium, bromideC48H44BrFeN3P2[α]D25=-368.7 (c 0.6, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (R,Sp)3-[4-Formyl-3-nitro-[(E)-[(1R)-1-[(2S)-1′,2-bis(diphenylphosphino)ferrocenyl]ethyl]imino]methyl]-1-methyl-1H-imidazolium, bromideC48H43BrFeN4O2P2[α]D25=-369.4 (c 0.6, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (R,Sp)3-[3-Formyl-[(E)-[(1R)-1-[(2S)-1′,2-bis(diphenylphosphino)ferrocenyl]ethyl]imino]methyl]-1-methyl-1H-imidazolium, bromideC48H44BrFeN3P2[α]D25=-372.9 (c 0.6, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (R,Sp)(S,E)-(3-(Benzyloxy)prop-1-ene-1,3-diyl)dibenzeneC22H20O[α]D25=+12.7 (c 3.3, toluene)Source of chirality: asymmetric synthesisAbsolute configuration: (S)(S,E)-(3-((4-Fluorobenzyl)oxy)prop-1-ene-1,3-diyl)dibenzeneC22H19FO[α]D25=+17.3 (c 0.7, toluene)Source of chirality: asymmetric synthesisAbsolute configuration: (S)(S,E)-(3-((2-Fluorobenzyl)oxy)prop-1-ene-1,3-diyl)dibenzeneC22H19FO[α]D25=+21.3 (c 0.7, toluene)Source of chirality: asymmetric synthesisAbsolute configuration: (S)(S,E)-(3-((3-Fluorobenzyl)oxy)prop-1-ene-1,3-diyl)dibenzeneC22H19FO[α]D25=+25.1 (c 0.7, toluene)Source of chirality: asymmetric synthesisAbsolute configuration: (S)(S,E)-(3-((4-Chlorobenzyl)oxy)prop-1-ene-1,3-diyl)dibenzeneC22H19ClO[α]D25=+22.5 (c 1.6, toluene)Source of chirality: asymmetric synthesisAbsolute configuration: (S)(S,E)-(3-((4-Bromobenzyl)oxy)prop-1-ene-1,3-diyl)dibenzeneC22H19BrO[α]D25=+28.9 (c 1.6, toluene)Source of chirality: asymmetric synthesisAbsolute configuration: (S)(S,E)-(3-((4-Methoxybenzyl)oxy)prop-1-ene-1,3-diyl)dibenzeneC23H22O2[α]D25=+2.2 (c 1.0, toluene)Source of chirality: asymmetric synthesisAbsolute configuration: (S)(S,E)-(3-((2-Methoxybenzyl)oxy)prop-1-ene-1,3-diyl)dibenzeneC23H22O2[α]D25=+20.5 (c 1.0, toluene)Source of chirality: asymmetric synthesisAbsolute configuration: (S)(S,E)-(3-((3-Methoxybenzyl)oxy)prop-1-ene-1,3-diyl)dibenzeneC23H22O2[α]D25=+18.5 (c 1.0, toluene)Source of chirality: asymmetric synthesisAbsolute configuration: (S)(S,E)-(3-((4-Methylbenzyl)oxy)prop-1-ene-1,3-diyl)dibenzeneC23H22O[α]D25=+17.5 (c 1.2, toluene)Source of chirality: asymmetric synthesisAbsolute configuration: (S)(S,E)-(3-((2-Methylbenzyl)oxy)prop-1-ene-1,3-diyl)dibenzeneC23H22O[α]D25=+7.5 (c 1.2, toluene)Source of chirality: asymmetric synthesisAbsolute configuration: (S)(S,E)-2-(((1,3-Diphenylallyl)oxy)methyl)furanC20H18O2[α]D25=+5.9 (c 1.0, toluene)Source of chirality: asymmetric synthesisAbsolute configuration: (S)(S,E)-(3-Phenoxyprop-1-ene-1,3-diyl)dibenzeneC21H18O[α]D25=+15.9 (c 1.0, toluene)Source of chirality: asymmetric synthesisAbsolute configuration: (S)(S,E)-(3-(4-Chlorophenoxy)prop-1-ene-1,3-diyl)dibenzeneC21H17ClO[α]D25=+15.8 (c 1.0, toluene)Source of chirality: asymmetric synthesisAbsolute configuration: (S)

Two new chiral stationary phases (CSP) were successfully prepared through bonding β-cyclodextrin (CD) derivatives modified by R-configuration groups (R-CPGCD, R-HMPGCD) to silica gel. Nineteen chiral nitro aromatic alcohol derivatives were separated under the polar organic and the reversed phase modes. Better enantioseparation was obtained in the reversed phase mode. The resolution values of the analytes ranged from 1.98 to 7.57 and from 2.19 to 8.14 on R-CPGCD and R-HMPGCD CSPs, respectively, using a mobile phase composed of methanol/water (v/v, 40/60). Better enantioseparation was obtained on R-HMPGCD CSP than on R-CPGCD CSP because of stronger hydrogen bonding and π–π interactions between the substituents on the cyclodextrin derivatives and the analytes. For different analytes, the increasing electronic density of the benzene ring was found to be favorable to the enantioseparation of the test analytes. The thermodynamic parameters showed that the enantioseparation of analytes was enthalpy-controlled and a lower temperature aided the enantiomeric separation of the solutes on the two CSPs. MD simulations were used to investigate the recognition mechanism between the chiral selectors and the analyte using R-, S-2-naphthalenemethanol and R-CPGCD and R-HMPGCD complexes as examples. S-2-naphthalenemethanol had the stronger interactions with R-CPGCD and R-HMPGCD than the R-isomer. The substituent derivatized on R-CPGCD and the cyclodextrin cavity contributed to the discrimination of the S-isomer, but only the derivatized group on R-HMPGCD was found to play a major role in separating prosess. In addition, the larger free energy deviation of the R- and S-isomers in the R-HMPGCD system brought about a higher resolution value (Rs = 8.14).

A novel chiral selector mono-6-deoxy-(2,4-dihydroxybenzimide)-β-CD (MDHB-β-CD) in which the derivatized group and the cavity of CD is linked by CH2–NC group, was successfully prepared, and the structural characteristics were determined by FT-IR, 1H and 13C NMR, MALDITOF-MS and element analysis. The corresponding stationary phase (CSP) was used in HPLC and the enantioseparation performance was investigated using chiral 1-phenyl-2-nitroethanol derivatives as test samples in the reverse-phase mode composed of methanol/water and acetonitrile/TEAA. Better separation abilities and excellent enantioselectivities (α > 1.26, RS > 1.73) were obtained on MDHB-β-CD CSP for these chiral compounds in the methanol/water mobile phase.Highlights► A novel chiral selector mono-6-deoxy-(2,4-dihydroxybenzimide)-β-CD was prepared. ► The structural characteristics of this chiral selector were determined. ► The corresponding chiral stationary phase was used to separate chiral compounds. ► Different compositions of the mobile phase were studied in separating. ► Excellent enantioseparations were obtained in the methanol/water mobile phase.

Four novel ILs functionalized β-cyclodextrins (β-CDs) were prepared by treating 6-tosyl-β-cyclodextrin with 1,2-dimethylimidazole or 1-amino-1,2,3-triazole, and bonded to silica gel to obtain chiral stationary phases (CSPs) to be used in high-performance liquid chromatography (HPLC). The separation performances of these CSPs were examined with 16 chiral aromatic alcohol derivatives and 2 racemic drugs in acetonitrile-based polar-organic mobile phase. Excellent enantioseparations were achieved for most of the analytes. The highest value of resolution factor calculated is 6.868. Comparison of the performance of 8a, 8b, 8c and 8d suggests that the positively charged imidazole group provides electrostatic interactions probably through strong H-bonding with the analytes, whereas the cationic triazole, which forms a weaker ion pair with its counter ion, is more capable of participating in ion-pairing interactions with acidic analytes. However, for compounds 12 and 13, which have larger molecular volumes than the other analytes, the interactions between analytes and both cationic imidazole and its counter ion of the selectors play an important role in the chiral resolution. Moreover, the high resolutions were found to depend on the properties of the cations and anions on the selectors in combination with the chiral recognition sites on the rim of the CD. The ionic strength in mobile phase affects the relative interactions between analytes and the chiral selector as well as between analytes and solvents.

Different substituent groups were introduced onto the rim of β-cyclodextrin through rigid CN bonds to form a series of imino-modified β-cyclodextrin derivatives: mono(6-deoxy-phenylimino)-β-cyclodextrin (BCD), mono(6-deoxy-isopropylimino)-β-cyclodextrin (YBCD), mono(6-deoxy-N-1-phenylethylimino)-β-cyclodextrin (R-,S-BYCD), mono[6-deoxy-N-1-(2-hydroxyl)-phenylethylimino]-β-cyclodextrin (R-,S-PGCD), heptakis(2,6-o-diamyl-6-deoxy-phenylimino)-β-cyclodextrin (WBCD), heptakis(2,6-o-diamyl-6-deoxyisopropylimino)-β-cyclodextrin (WYBCD) and heptakis[2,6-o-diamyl-6-deoxy-R-(-)-N-1-phenylethylimino)-β-cyclodextrin (WRBYCD). The obtained derivatives were then bonded to silica gel and used in high-performance liquid chromatography (HPLC) as chiral stationary phases (CSPs). The separation performance of these CSPs was examined by separating disubstituted benzenes, amino acids, ferrocene derivatives andchiral aromatic alcohol compounds. Satisfactory separation results were obtained for most of the compounds. The values for selectivity factors can reach up to 8.50 and 8.16 for separating positional isomers and ferrocene derivatives, respectively, and the best resolution was 6.89 for aromatic alcohol derivative separations. Molecular dynamics (MD) simulations were carried out for chiral discrimination of rac-N-benzoyl-phenylglycinol on S-PGCD CSP to study the recognition mechanism. MD simulation results show that the average free-energy of interaction is −1304.83 kcal/mol for the l-enantiomer and S-PGCD and −1324.23 kcal/mol for the d-enantiomer and S-PGCD. In the recognition stage, the l-enantiomer moves along the exterior of the cyclodextrin cavity from the wider edge to the narrower edge of cyclodextrin whereas the d-enantiomer moves slightly towards the cavity. The l-enantiomer thus is separated first due to weaker interaction with S-PGCD.

A series of novel quarternary ammonium salt-modified chiral ferrocenylphosphine-imine ligands have been synthesized and the molecular structure of BIT5 has been determined by single-crystal X-ray diffraction. The applicability of these ligands in asymmetric C∗–C and C∗–N bond formation was demonstrated. High enantioselectivity was obtained in the Pd-catalyzed asymmetric substitution of 1,3-diphenyl-2-propenyl acetate, with dimethyl malonate (up to 94.6% ee) and benzylamine (up to 92.6% ee).4-[(E)-[[(1R)-1-[(2S)-2-(Diphenylphosphino)ferrocenyl]ethyl]imino]methyl]-N,N,N-trimethyl-benzenaminium, iodideC34H36FeIN2P[α]D = −354.3 (c 0.6, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (R,Sp)4-[(E)-[[(1R)-1-[(2S)-2-(Diphenylphosphino)ferrocenyl]ethyl]imino]methyl]-N,N,N-trimethyl-benzenaminium, bromideC34H36BrFeN2P[α]D = −369.0 (c 0.6, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (R,Sp)4-[(E)-[[(1R)-1-[(2S)-2-(Diphenylphosphino)ferrocenyl]ethyl]imino]methyl]-N,N,N-trimethyl-benzenaminium, trifluoromethane sulfonateC34H36F3FeN2O3PS[α]D = −353.9 (c 0.6, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (R,Sp)4-[(E)-[[(1R)-1-[(2S)-2-(Diphenylphosphino)ferrocenyl]ethyl]imino]methyl]-N,N,N-trimethyl-benzenaminium, p-toluenesulfonateC41H43F3FeN2O3PS[α]D = −368.3 (c 0.6, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (R,Sp)4-[(E)-[[(1R)-1-[(2S)-2-(Diphenylphosphino)ferrocenyl]ethyl]imino]methyl]-N,N,N-trimethyl-benzenaminium, acetateC36H39FeN2O2P[α]D = −345.0 (c 0.6, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (R,Sp)4-[(E)-[[(1R)-1-[(2S)-2-(Diphenylphosphino)ferrocenyl]ethyl]imino]methyl]-N,N,N-trimethyl-benzenaminium, nitrateC34H36FeN3O3P[α]D = −355.7 (c 0.6, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (R,Sp)4-[(E)-[[(1R)-1-[(2S)-2-(Diphenylphosphino)ferrocenyl]ethyl]imino]methyl]-N,N,N-trimethyl-benzenaminium, hexafluorophosphateC34H36F6FeN2P2[α]D = −364.75 (c 0.6, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (R,Sp)3-[(E)-[[(1R)-1-[(2S)-2-(Diphenylphosphino)ferrocenyl]ethyl]imino]methyl]-N,N,N-trimethyl-benzenaminium, iodideC34H36FeIN2P[α]D = −347.2 (c 0.6, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (R,Sp)2-[(E)-[[(1R)-1-[(2S)-2-(Diphenylphosphino)ferrocenyl]ethyl]imino]methyl]-N,N,N-trimethyl-benzenaminium, iodideC34H36FeIN2P[α]D = −339.85 (c 0.6, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (R,Sp)4-[(E)-[[(1R)-1-[(2S)-2-(Diphenylphosphino)ferrocenyl]ethyl]imino]methyl]-N,N,N-trimethyl-benzenemethanaminium, iodideC35H38FeIN2P[α]D = −352.3 (c 0.6, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (R,Sp)N-[4-[(E)-[[(1R)-1-[(2S)-2-(Diphenylphosphino)ferrocenyl]ethyl]imino]methyl]]-N,N-dimethyl-benzenemethanaminium, bromideC40H40BrFeN2P[α]D = −376.25 (c 0.6, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (R,Sp)(S,E)-Dimethyl 2-(1,3-diphenylallyl)malonateC20H20O4[α]D = −17.0 (c 1.5, ethanol, 94.6% ee)Source of chirality: asymmetric synthesisAbsolute configuration: (S)(S,E)-Diethyl 2-(1,3-diphenylallyl)malonateC22H24O4[α]D = −16.9 (c 1.0, CHCl3, 94.0% ee)Source of chirality: asymmetric synthesisAbsolute configuration: (S)(S,E)-Diethyl 2-(1,3-diphenylallyl)-2-methylmalonateC23H26O4[α]D = −29.9 (c 0.6, CHCl3, 91.0% ee)Source of chirality: asymmetric synthesisAbsolute configuration: (S)(S,E)-Dibenzyl 2-(1,3-diphenylallyl)malonateC32H28O4[α]D = −7.9 (c 1.6, CHCl3, 91.6% ee)Source of chirality: asymmetric synthesisAbsolute configuration: (S)(R,E)-N-Benzyl-1,3-diphenylprop-2-en-1-amineC22H21N[α]D = −18.8 (c 0.15, CHCl3, 92.6% ee)Source of chirality: asymmetric synthesisAbsolute configuration: (R)(R,E)-N-(1,3-Diphenylallyl)benzohydrazideC22H20N2O[α]D = −35.7 (c 0.73, CHCl3, 91.4% ee)Source of chirality: asymmetric synthesisAbsolute configuration: (R)(R,E)-N-(1,3-Diphenylallyl)phthalimideC23H17NO2[α]D = −19.7 (c 1.7, CHCl3, 89.9% ee)Source of chirality: asymmetric synthesisAbsolute configuration: (R)(R,E)-1-(1,3-Diphenylallyl)pyrrolidineC19H21N[α]D = −2.4 (c 1.0, CHCl3, 40.2% ee)Source of chirality: asymmetric synthesisAbsolute configuration: (R)(R,E)-4-(1,3-Diphenylallyl)morpholineC19H21NO[α]D = −3.8 (c 0.34, CHCl3, 33.5% ee)Source of chirality: asymmetric synthesisAbsolute configuration: (R)

Here, we report a convenient access to diastereoselective synthesis of polysubstituted pyrrolidines bearing a unique spiro quaternary center at the C-2 position and another quaternary center at C-4. The synthesis system, CuII/P, N-Ligand-catalyzed 1, 3-dipolar cycloaddition, by employing homoserine lactone derived cyclic imino esters as the dipoles and α, α, β-trisubstituted olefins as the dipolarophlies, provides exo-spiro-pyrrolidines with good yields, high diastereoselectivities (up to >98:2 dr) and performs well for a broad scope of substrates.

A novel energetic heat-resistant explosive, 1-(3,5-dinitro-1H-pyrazol-4-yl)-3-nitro-1H-1,2,4-triazol-5-amine (HCPT), has been synthesized along with its salts. An intensive characterization of the compounds is given, including 1H and 13C NMR spectroscopy, IR spectroscopy, and elemental analysis. The crystal structures of neutral HCPT (3), its triaminoguanidinium salt (10), 3,4,5-triamino-1,2,4-triazolium salt (12), and copper(II) complex (16) were determined by single-crystal X-ray diffraction. The physicochemical properties of the compounds, such as density, thermal stability, and sensitivity towards impact and friction were evaluated; all energetic compounds exhibited excellent thermal stabilities with decomposition temperatures ranging from 215 °C to 340 °C, and high positive heats of formation between 622.8 kJ mol−1 and 1211.7 kJ mol−1. The detonation pressures and velocities for the energetic compounds were calculated using EXPLO5 (V6.01) based on experimental densities and calculated heats of formation, and the corresponding values were in the ranges of 26.5 GPa to 37.8 GPa and 8236 m s−1 to 9167 m s−1. Based on thermal stability values and energetic parameters, compounds 3 and 7 were superior to those of all of the commonly used heat-resistant explosives, which may find potential application as heat-resistant energetic materials.

The combination of superior energetic structural fragments is a feasible route to design new energetic materials. In this work, selected metal and nitrogen-rich salts based on 3,4-dinitro-1-(1H-tetrazol-5-yl)-1H-pyrazol-5-amine (HANTP) are prepared and characterized by 1H/13C NMR, IR spectroscopy, and elemental analysis. The crystal structures of neutral HANTP (2), and its potassium (4), sodium (5), ammonium (6), and guanidinium (9) salts are determined by single-crystal X-ray diffraction, and their properties (density, thermal stability, and sensitivity towards impact and friction) are investigated. The detonation properties are evaluated by the EXPLO5 (v6.01) program using the measured density and calculated heat of formation (Gaussian 03). All compounds exhibit thermal stabilities with decomposition temperatures ranging from 171 to 270 °C, high densities (1.61–2.92 g cm−3), and high positive heats of formation (630.4–1275.2 kJ mol−1). The inorganic salts (4 and 5) assume particular structures (two-dimensional and one-dimensional metal–organic frameworks, respectively). Suitable impact and friction sensitivities and being free of toxic metals place these compounds within the green primary explosives group and several of the new organic salts exhibit detonation and other properties that compete with, or exceed the performance of those of HMX.

To reach the long-term, strongly desired goal of high energy density materials (HEDM), a novel N-bridged structure of N-(3,5-dinitro-1H-pyrazol-4-yl)-1H-tetrazol-5-amine, and its selected nitrogen-rich energetic salts are designed and synthesized. All compounds are fully characterized by 1H and 13C NMR (in some cases, 15N NMR) spectroscopy, IR spectroscopy, HRMS and elemental analysis. Of these, salts 6·H2O and 10 are further confirmed by single-crystal X-ray diffraction. The densities of these compounds ranged from 1.67 to 1.86 g cm−3. All energetic salts exhibit excellent thermal stabilities with decomposition temperatures ranging from 216 to 299 °C and all are insensitive to impact. Decomposition of these thermally stable compounds (salts 2, 3, and 4) occurs at 299, 296, and 290 °C, respectively. Theoretical performance calculations (Gaussian 03 and EXPLO5 v6.01) provide detonation pressures and velocities for the energetic salts in the ranges 25.9–37.4 GPa and 8264–9364 m s−1, respectively; six of the energetic compounds have detonation velocities >9000 m s−1. Notably, the unique overall performance of salt 4 thus exceeds those of commonly used explosives such as HMX. Thus, due to its insensitivity (IS > 40 J, FS = 360 N), fairly high detonation velocity (vD = 9364 m s−1), exceptional thermal stability (Td = 290 °C), and high nitrogen content (N = 56.4%), salt 4 is a prospective candidate for a new class of insensitive, highly energetic explosives.

A new family of nitrogen-rich energetic salts based on 3-nitro-1-(2H-tetrazol-5-yl)-1H-1,2,4-triazol-5-amine (HANTT) were synthesized and characterized by 1H and 13C nuclear magnetic resonance, infrared spectroscopy and elemental analysis. The crystal structures of neutral HANTT (2), its guanidinium salt (3), and 1,5-diamino-tetrazolium salt (9) were determined by single-crystal X-ray diffraction. All energetic salts exhibit excellent thermal stabilities with decomposition temperatures ranging within 264–321 °C and are insensitive to impact, friction and electrostatic discharge. The densities of salts 3–10 ranged from 1.65 g cm−3 to 1.81 g cm−3. Theoretical performance calculations (Gaussian 03 and EXPLO5) provided detonation pressures and velocities for the energetic salts within the ranges of 22.6–32.6 GPa and 7742–8779 m s−1, respectively, making them competitive energetic materials.

Organometallic and organo-catalysts are cooperatively at work in the enantioselective synthesis of dibenzopyran derivatives; palladium/norbornene and a cinchona alkaloid base guarantee good yields and satisfactory enantioselectivities in a one-pot reaction.

Functional imidazolium ionic liquids have been developed as a new class of versatile catalysts. C2-symmetric imidazolium-tagged bis(oxazoline) ligands were prepared, and the anions of the ligands were altered. The catalysts based on the new ligands and Cu(OAc)2·H2O were applied in asymmetric Henry reactions between various aldehydes 3 and CH3NO24. The catalysts achieved a high level of enantioselectivity; product (R)-5n was attained at 94% ee in MeOH. Moreover, the catalyst could be recycled 6 times without an obvious loss of activity or enantioselectivity. In addition, a theoretical mechanistic study was conducted to explain the origin of the enantioselectivity.

Energetic salts based on bis(N-dinitroethyl)aminofurazan were synthesised. All salts were fully characterised using 1H and 13C multinuclear NMR spectroscopy, infrared spectroscopy, elemental analysis, density analysis, and differential scanning calorimetry. These salts exhibited reasonable physical properties, such as high densities (1.72 g cm−3 to 1.94 g cm−3) and low solubilities in water. Based on the experimental densities, the detonation pressures and velocities of the energetic salts were calculated, ranging from 26.1 GPa to 39.4 GPa and 8055 m s−1 to 9388 m s−1, respectively. These value were higher than those of TNT and similar to those of RDX. The thermal stability and thermal kinetic parameters of the new energetic salts were also evaluated using Kissinger’s and Ozawa’s methods, coupled with DSC.

Novel super-highly energetic bis(2,2-dinitroethyl)nitramine-based salts exhibiting excellent physical and detonation properties, such as low solubility in common solvents, moderate thermal stabilities, high densities, high detonation pressures and detonation velocities, were synthesized and fully characterized. The densities of the energetic salts range between 1.77 and 2.02 g cm−3 as measured using a gas pycnometer. The detonation pressures and velocities as calculated by the EXPLO5 code are in the range 31.5–46.2 GPa and 8586–10004 m s−1, which make them competitive super-highly energetic materials.

The unique and facile synthesis of 7-nitro-4-oxo-4,8-dihydro-[1,2,4]triazolo[5,1-d][1,2,3,5]tetrazine 2-oxide (HBCM) and a proposed mechanism for its formation are described. The hygroscopicity of HBCM was overcome by transforming it into salts. The energetic salts of HBCM were characterized by 1H and 13C nuclear magnetic resonance spectroscopy, infrared spectroscopy, differential scanning calorimetry (DSC) and elemental analysis. The crystal structures of the sodium and guanidinium salts were determined by single-crystal X-ray diffraction. The densities of the salts ranged from 1.77 to 1.97 g cm−3. Most of the energetic salts decomposed above 230 °C and tended to be insensitive to impact, friction and electrostatic discharge. Theoretical performance calculations (Gaussian 03 and EXPLO5) for the energetic salts provide detonation pressures and velocities within the ranges of 25.2 to 39.5 GPa and 7856 to 9069 m s−1, respectively. The hydroxylammonium salt showed high density (1.97 g cm−3), acceptable decomposition temperature (Td = 197 °C), low sensitivities, and excellent detonation velocity (9069 m s−1) and pressure (39.5 GPa), which suggests that it has the potential to be used as a high-energy-density material.

Correction for ‘A novel enantioselective synthesis of 6H-dibenzopyran derivatives by combined palladium/norbornene and cinchona alkaloid catalysis’ by Di Xu et al., Org. Biomol. Chem., 2015, DOI: 10.1039/c4ob02551b.

New polynitro-substituted bispyrazoles were synthesised and fully characterised in this study. Ammonium 4-(4′-amino-3′,5′-dinitro-1′-pyrazol)-3,5-dinitropyrazole (3), 4-(4′-amino-3′,5′-dinitro-1′-pyrazol)-1-amino-3,5-initropyrazole (6), diaminoguanidinium 4-(4′-amino-3′,5′-dinitro-1′-pyrazol)-3,5-dinitropyrazole (9), and 3,4,5-triamino-1,2,4-triazolium 4-(4′-amino-3′,5′-dinitro-1′-pyrazol)-3,5-dinitropyrazole (12) were further confirmed using single-crystal X-ray diffraction. The compounds exhibited excellent thermal stabilities, insensitivities and high detonation performance. The measured LC50 of the compounds suggested that their toxicities were lower than that of TNT and that for compound 3 even lower than that of TATB. Compound 5 demonstrates unprecedented overall performance: higher detonation velocity (VD = 8760–8981 m s−1), detonation heat (Qv = 7551 kJ kg−1) and explosive power (A = 1712 kJ g−1) than RDX, a decomposition temperature (Td = 297 °C) higher than that of HMX, and much lower toxicity (LC50 = 7 μg mL−1) than that of TNT, ranking it in a new generation of heat resistant, less sensitive and low environmental impact high energetic materials.

Energetic salts based on 4,4′-oxybis[3,3′-(1H-5-tetrazol)]furazan were readily synthesized and fully characterized by NMR (1H, 13C), IR spectroscopy, elemental analysis, and differential scanning calorimetry (DSC). Bis(guanidinium) (6), bis(aminoguanidinium) (7), bis(diaminoguanidinium) (8) salts and carbonic dihydrazidinium(HBTFOF)2 (13) were further confirmed by single-crystal X-ray diffraction. All the salts exhibit excellent thermal stabilities with decomposition temperatures over the range 212–289 °C. The densities of the energetic salts ranged between 1.64 and 1.86 g cm−3. The detonation pressures and velocities were calculated to be between 19.7 and 30.8 GPa and 7266–8624 m s−1, respectively. Impact sensitivities were found to be in the range 5–36 J. The relationship between salt structure and thermal stability was studied by NBO analysis for compounds 6, 7, and 8.