New Frontiers in Nitramine Reactivity via the Mitsunobu Reaction.

-Nitro derivatives of primary alkyl, aryl and heteroarylamines can be directly alkylated with functionalized alcohols under Mitsunobu conditions at the and/or atoms of the nitramino moiety to give secondary nitramines or 1-alkoxydiazene 1-oxides, respectively.

First Alliance of Pyrazole and Furoxan Leading to High-Performance Energetic Materials.

Nitrogen heterocyclic scaffolds retain their leading position as valuable building blocks in material science, particularly for the design of small-molecule energetic materials. However, the search for more balanced combinations of directly linked heterocyclic cores is far from being exhausted and aims to reach ideally balanced high-energy substances. Herein, we present the synthetic route to novel pyrazole-furoxan framework enriched with nitro groups and demonstrate a promising set of properties, viz.

Charge-compensated -carborane derivatives in the synthesis of iron(II) bis(dicarbollide) complexes.

A series of stable iron(II) bis(dicarbollide) derivatives [8,8'-(RNHC(Et)HN)-3,3'-Fe(1,2-CBH)] (R = Pr, R = Ph, (CH)OH, (CH)OH, (CH)NMe) was prepared starting from FeCl or [FeCl(dppe)] and the corresponding -carboranyl amidines [10-RNHC(Et)HN-7,8-CBH]. In a similar way, the reactions of the oxonium derivatives of -carborane with FeCl in tetrahydrofuran in the presence of -BuOK lead to the corresponding stable oxonium derivatives iron(II) bis(dicarbollide) [8,8'-(RR'O)-3,3'-Fe(1,2-CBH)] (RR' = (CH), (CH)O(CH), (CH); R = R' = Et), which can be alternatively prepared by the reaction of the parent iron(II) bis(dicarbollide) with tetrahydrofuran or 1,4-dioxane in the presence of MeSO. The cyclic voltammetry studies of the synthesized iron(II) bis(dicarbollide) derivatives revealed that the introduction of amidinium and oxonium substituents leads to a significant increase in the Fe/Fe redox potential relative to the parent iron(II) bis(dicarbollide).

Nickel(II) and Palladium(II) Complexes with η:κ()-Coordinated Dicarbollide Ligands Containing Pendant Pyridine Group.

A series of - and -substituted -carborane derivatives with a pendant pyridyl group was prepared. The synthesized compounds were used as ligands in the complexation reactions with bis(triphenylphosphine)nickel(II) and palladium(II) chlorides to give six new metallacomplexes with unusual η:κ()-coordination of the metal center. The single crystal structures of 1-(NCH-2'-S)-1,2-CBH, 1-(NCH-2'-CHS)-1,2-CBH, Cs [7-(NCH-2'-CHS)-7,8-CBH] - and -carboranes and 3-PhP-3-(4(7)-NCH-2'-S)--3,1,2-NiCBH and 3-PhP-3-(4(7)-NCH-2'-CHS)--3,1,2-NiCBH metallacarboranes were determined using single crystal X-ray diffraction.

Energetic Polymer Possessing Furazan, 1,2,3-Triazole, and Nitramine Subunits.

A [3 + 2] cycloaddition reaction using dialkyne and diazide comonomers, both bearing explosophoric groups, to synthesize energetic polymers containing furazan and 1,2,3-triazole ring as well as nitramine group in the polymer chain have been described. The developed solvent- and catalyst-free approach is methodologically simple and effective, the comonomers used are easily available, and the resulting polymer does not need any purification. All this makes it a promising tool for the synthesis of energetic polymers.

How the Position of Substitution Affects Intermolecular Bonding in Halogen Derivatives of Carboranes: Crystal Structures of 1,2,3- and 8,9,12-Triiodo- and 8,9,12-Tribromo -Carboranes.

The crystal structures of two isomeric triiodo derivatives of -carborane containing substituents in the three most electron-withdrawing positions of the carborane cage, 1,2,3-I-1,2-CBH, and the three most electron-donating positions, 8,9,12-I-1,2-CBH, as well as the crystal structure of 8,9,12-Br-1,2-CBH, were determined by single-crystal X-ray diffraction. In the structure of 1,2,3-I-1,2-CBH, an iodine atom attached to the boron atom (position 3) donates its lone pairs simultaneously to the σ-holes of both iodine atoms attached to the carbon atoms (positions 1 and 2) with the I⋯I distance of 3.554(2) Å and the C-I⋯I and B-I⋯I angles of 169.

Energetic [1,2,5]oxadiazolo [2,3-]pyrimidin-8-ium Perchlorates: Synthesis and Characterization.

A convenient method to access the above perchlorates has been developed, based on the cyclocondensation of 3-aminofurazans with 1,3-diketones in the presence of HClO. All compounds were fully characterized by multinuclear NMR spectroscopy and X-ray crystal structure determinations. Initial safety testing (impact and friction sensitivity) and thermal stability measurements (DSC/DTA) were also carried out.

Synthesis of 4-trifluoromethyl-2-chromenes the reaction of 2-(trifluoroacetyl)phenols with vinyltriphenylphosphonium chloride.

Substituted on the benzene ring 4-CF-2-chromenes have been prepared from substituted 2-(trifluoroacetyl)phenols and vinyltriphenylphosphonium chloride according to the Schweizer protocol in moderate to excellent yields. The influence of the type and the position of aromatic ring substituents on yields of 4-CF-2-chromenes have been investigated. It has been shown that 4-CF-2-chromenes are convenient precursors to 4-CF-coumarins.

New approaches to the functionalization of the 1-carba--decaborate anion.

Two new approaches to the functionalization of the 1-carba--decaborate anion [1-CBH] at boron atoms the ring-opening of its 1,4-dioxane derivative with various nucleophiles and Pd-catalysed cross-coupling of its iodo derivative with aromatic amines and heteroaromatics were developed.

Energetic Co-Crystal of a Primary Metal-Free Explosive with BTF. Ideal Pair for Co-Crystallization.

Co-crystallization is an elegant technique to tune the physical properties of crystalline solids. In the field of energetic materials, co-crystallization is currently playing an important role in the engineering of crystals with improved performance. Here, based on an analysis of the structural features of the green primary explosive, tetramethylammonium salt of 7-oxo-5-(trinitromethyl)-4,5,6,7-tetrahydrotetrazolo[1,5-a][1,3,5]triazin-5-ide (), a co-former such as the powerful secondary explosive, benzotrifuroxan (BTF, ), has been proposed to improve it.

Synthesis of 3-Aryl--carboranes with Sensitive Functional Groups.

A simple and efficient method was developed for the one-pot synthesis of 3-aryl derivatives of -carborane with sensitive functional groups using 3-iodo--carborane and aryl zinc bromides that were generated in situ. A series of 3-aryl--carboranes, including those containing nitrile and ester groups, 3-RCH-1,2-CBH (R = -Me, -NMe, -OCHOMe, -OMe, -CN, -CN, -COOEt, -COOEt, -COOEt) was synthesized using this approach. The solid-state structures of 3-RCH-1,2-CBH (R = -OMe, -CN, and -CN) were determined by single crystal X-ray diffraction.

Synthesis of Zwitter-Ionic Conjugate of -Carborane with Cholesterol.

9-HC≡CCHMeN--7,8-CBH, a previously described carboranyl terminal alkyne, was used for the copper(I)-catalyzed azide-alkyne cycloaddition with azido-3β-cholesterol to form a novel zwitter-ionic conjugate of -carborane with cholesterol, bearing a 1,2,3-triazol fragment. The conjugate of -carborane with cholesterol, containing a charge-compensated group in the linker, can be used as a precursor for the preparation of liposomes for BNCT (Boron Neutron Capture Therapy). The solid-state molecular structure of a -carborane derivative with the 9-MeN(CH)MeN--7,8-CBH terminal dimethylamino group was determined by single-crystal X-ray diffraction.

Synthesis of Boronated Amidines by Addition of Amines to Nitrilium Derivative of Cobalt Bis(Dicarbollide).

A series of novel cobalt bis(dicarbollide) based amidines were synthesized by the nucleophilic addition of primary and secondary amines to highly activated B-N≡C-R triple bond of the propionitrilium derivative [8-EtC≡N-3,3'-Co(1,2-CBH)(1',2'-CBH)]. The reactions with primary amines result in the formation of mixtures of and isomers of amidines, whereas the reactions with secondary amines lead selectively to the -isomers. The crystal molecular structures of -[8-EtC(NMe)=HN-3,3'-Co(1,2-CBH)(1',2'-CBH)], -[8-EtC(NEt)=HN-3,3'-Co(1,2- CBH)(1',2'-CBH)] and -[8-EtC(NCH)=HN-3,3'-Co(1,2-CBH)(1',2'-CBH)] were determined by single crystal X-ray diffraction.

Synthesis and Antioxidant Capacity of Some Derivatives of Sesamol at the C-6 Position.

Several synthetic approaches (aminomethylation, alkylation, condensation, etc.) have been used to synthesize derivatives based on the sesamol (1), natural phenol. The set of methods, including the study of antioxidant activity (AOA) by the ability to inhibit the initiated oxidation of animal lipids, radical scavenging activity, Fe -chelation ability, as well as a comparative assessment of membrane-protective activity under the conditions of H O -induced hemolysis of mice red blood cells (RBCs), was used to analyze the antioxidant potential of the synthesized compounds.

Synthesis of Bis(Carboranyl)amides 1,1'-μ-(CHNH(O)C(CH)-1,2-CBH) ( = 0, 1) and Attempt of Synthesis of Gadolinium Bis(Dicarbollide).

Bis(carboranyl)amides 1,1'-μ-(CHNH(O)C(CH)-1,2-CBH) ( = 0, 1) were prepared by the reactions of the corresponding carboranyl acyl chlorides with ethylenediamine. Crystal molecular structure of 1,1'-μ-(CHNH(O)C-1,2-CBH) was determined by single crystal X-ray diffraction. Treatment of bis(carboranyl)amides 1,1'-μ-(CHNH(O)C(CH)-1,2-CBH) with ammonium or cesium fluoride results in partial deboronation of the -carborane cages to the -carborane ones with formation of [7,7'(8')-μ-(CHNH(O)C(CH)-7,8-CBH)].

The unexpected reactivity of 9-iodo-nido-carborane: from nucleophilic substitution reactions to the synthesis of tricobalt tris(dicarbollide) Na[4,4',4''-(MeOCHCHO)-3,3',3''-Co(μ-O)(μ-S)(1,2-CBH)].

An unusual reactivity of 9-iodo-nido-carborane [9-I-7,8-CBH] towards nucleophiles under strong basic conditions was revealed. The nucleophilic substitution of iodine with O- and N-nucleophiles results in [9-RO-7,8-CBH] (R = H, CHCHOMe) and [9-L-7,8-CBH] (L = Py, NEt, MeNCHCHNMe), respectively. Reaction of [9-I-7,8-CBH] with CoCl in 1,2-dimethoxyethane in the presence of t-BuOK, depending on the order of addition of the reagents, leads either to a diastereomeric mixture of diiodo derivatives cobalt bis(dicarbollide) rac-[4,4'-I-3,3'-Co(1,2-CBH)] and meso-[4,7'-I-3,3'-Co(1,2-CBH)] or to the corresponding mixture of 2-methoxyethoxy derivatives rac-[4,4'-(MeOCHCHO)-3,3'-Co(1,2-CBH)] and meso-[4,7'-(MeOCHCHO)-3,3'-Co(1,2-CBH)].

The First Nickelacarborane with - Structure.

The first nickelacarborane with structure [10',11'-(Py)-3,9'-Ni(1,2-CBH)(7',8'-CBH)] was isolated from the reaction of nickel(IV) bis(dicarbollide) with pyridine. The molecular structure of this complex was determined by single crystal X-ray diffraction. The nickel atom is a common vertex for the -NiCB cluster and the -NCB cluster where it is located together with carbon atoms in the open NiCB pentagonal face.

Bis(dicarbollide) Complexes of Transition Metals as a Platform for Molecular Switches. Study of Complexation of 8,8'-Bis(methylsulfanyl) Derivatives of Cobalt and Iron Bis(dicarbollides).

Complexation of the 8,8'-bis(methylsulfanyl) derivatives of cobalt and iron bis(dicarbollides) [8,8'-(MeS)-3,3'-M(1,2-CBH)] (M = Co, Fe) with copper, silver, palladium and rhodium leads to the formation of the corresponding chelate complexes, which is accompanied by a transition from the to the conformation of the bis(dicarbollide) complex. This transition is reversible and can be used in design of coordination-driven molecular switches based on transition metal bis(dicarbollide) complexes. The solid-state structures of {(PhP)ClPd[8,8'- (MeS)-3,3'-Co(1,2-CBH)-κ-S,S']} and {(COD)Rh[8,8'-(MeS)-3,3'-Co(1,2-CBH)-κ-S,S']} were determined by single crystal X-ray diffraction.

Nitration of Azasydnones and Azasydnonimines: A Method for the Functionalization of Aryl Derivatives.

The first example of functionalization of mesoionic 3-R-1,2,3,4-oxatriazol-5-ones and 3-substituted-1,2,3,4-oxatriazol-5-imines (azasydnones and azasydnonimines, respectively) by the electrophilic reaction without destruction of the oxatriazole ring is reported. Nitration of a range of aryl derivatives bearing various electron donating and withdrawing substituents at the ortho-, meta- and para-positions using HNO /H SO mixtures has been assessed in order to develop an approach for the synthesis of corresponding nitroaryl derivatives. Whereas nitration occurs meta to the azasydnone ring, the regioselectivity of the electrophilic substitution can be affected by the nature of the substituent attached to the aryl ring, and a variety of polyfunctionalized derivatives can be readily accessed by using this methodology, which may have applications in the target-oriented synthesis.

Synthesis and Structure of Methylsulfanyl Derivatives of Nickel Bis(Dicarbollide).

Symmetrically and unsymmetrically substituted methylsulfanyl derivatives of nickel(III) bis(dicarbollide) (BuN)[8,8'-(MeS)-3,3'-Ni(1,2-CBH)], (BuN)[4,4'-(MeS)-3,3'-Ni(1,2-CBH)], and (BuN)[4,7'-(MeS)-3,3'-Ni(1,2-CBH)] were synthesized, starting from [Ni(acac)] and the corresponding methylsulfanyl derivatives of -carborane (BuN)[10-MeS-7,8-CBH] and (BuN)[10-MeS-7,8-CBH]. Structures of the synthesized metallacarboranes were studied by single-crystal X-ray diffraction and quantum chemical calculations. The symmetrically substituted 8,8'-isomer adopts conformation stabilized by two pairs of intramolecular C-H···S hydrogen bonds between the dicarbollide ligands.

Synthesis and Characterization of 3-(5-(Fluorodinitromethyl)-1H-1,2,4-triazol-3-yl)-4-nitrofurazan: A Novel Promising Energetic Component of Boron-based Fuels for Rocket Ramjet Engines.

The synthesis of a new energetic 1,2,4-triazole compound bearing nitrofurazanyl and fluorodinitromethyl units, which may find use as a component for rocket ramjet engines (RRE), is described. The target product was prepared in a four-step process applying oxidation/nitration/decarboxylation/fluorination reactions and is fully characterized. Its density and structural features were uniquely determined by X-ray analysis.

Diastereoselective Synthesis of Triterpenoid 1,2,4-Trioxolanes by Griesbaum Co-ozonolysis.

Diastereoselective synthesis of triterpenoid 1,2,4-trioxolanes by Griesbaum co-ozonolysis was shown for the first time. Ozonolysis of 2-methoxyoximes (--isomers mixture) of allobetulin or methyl oleanoate with CF-ketones resulted in asymmetrical spiro-1,2,4-trioxolanes as mixtures of diastereomers in yields up to 80-85%. The configuration of the spiro-C-2 center of individual ozonides was determined by 2D NMR spectra and X-ray crystallographic analysis.

Optimization of pyrrolo[3,4-f]indole-5,7-dione and indole-5,6-dicarbonitrile derivatives as inhibitors of monoamine oxidase.

In recent studies, we have investigated the monoamine oxidase (MAO) inhibition properties of pyrrolo[3,4-f]indole-5,7-dione and indole-5,6-dicarbonitrile derivatives. Since numerous high potency MAO inhibitors are present among these chemical classes, the present study synthesizes 44 additional derivatives in an attempt to further derive structure-activity relationships (SARs) and to establish optimal substitution patterns for MAO inhibition. The results show that, with the exception of one compound, all indole-5,6-dicarbonitrile derivatives (10) exhibit submicromolar IC values for the inhibition of MAO, with the most potent MAO-A inhibitor exhibiting an IC value of 0.

Assembly of Tetrazolylfuroxan Organic Salts: Multipurpose Green Energetic Materials with High Enthalpies of Formation and Excellent Detonation Performance.

A series of highly energetic organic salts comprising a tetrazolylfuroxan anion, explosophoric azido or azo functionalities, and nitrogen-rich cations were synthesized by simple, efficient, and scalable chemical routes. These energetic materials were fully characterized by IR and multinuclear NMR ( H, C, N, N) spectroscopy, elemental analysis, and differential scanning calorimetry (DSC). Additionally, the structure of an energetic salt consisting of an azidotetrazolylfuroxan anion and a 3,6,7-triamino-7H-[1,2,4]triazolo[4,3-b][1,2,4]triazolium cation was confirmed by single-crystal X-ray diffraction.