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A general approach for preparation of two types of polyfunctionalized 3-trifluoromethylpyrazoles is reported. The protocol comprises (3 + 2)-cycloaddition of the in situgenerated trifluoroacetonitrile imines with enones leading to trans-configured 5-acyl-pyrazolines in a fully regio- and diastereoselective manner. Initially formed cycloadducts were aromatized by treatment with manganese dioxide. Depending on the solvent used, the oxidation step either led to fully substituted pyrazoles (DMSO) or proceeded via a deacylative pathway to afford 1,3,4-trisubstituted derivatives (hexane) with excellent selectivity.

Readily available 2-unsubstituted imidazole N-oxides were examined as starting materials for the preparation of fully substituted 1,4,5-aryl/alkyl 2-trifluoromethylsulfanyl-imidazoles. Whereas activation of the N-oxide function followed by attempted nucleophilic addition of the –SCF3was in vain, the alternative approach involving “sulfur transfer reaction” and subsequent electrophilic trifluoromethylation with Togni reagent provided target products in high yield via a one-pot procedure. The structure of representative enantiomerically pure imidazol-2-yl trifluoromethyl sulfide was confirmed by X-ray analysis.

A synthetically useful approach for one-pot preparation of 1-aryl-3-trifluoromethylpyrazoles using in situ generated nitrile imines and mercaptoacetaldehyde applied as 1 equiv of acetylene is presented. This protocol comprises (3 + 3)-annulation of the mentioned reagents to form 5,6-dihydro-5-hydroxy-4H-1,3,4-thiadiazine, followed by cascade dehydration/ring contraction reactions with p-TsCl. In addition, representative nonfluorinated analogues functionalized with Ph, Ac, and CO2Et groups at the C(3)-position of the pyrazole ring were also prepared by the devised method.

The article presents results of long years operational research of the real object localized in the maritime port. The aim of research was the identification of phenomena occurring between grain cargoes and handling equipment. The properties of grains and related products make, that in devices for internal transport systems take place the phenomena of intense erosive wear. The corrosive phenomena, typical for moist environment in the port; additionally speed up the destruction of the steel elements of internal transport system inside the grain silos. There has been discussed the main mechanisms of wear, indicating the fundamental role of the corrosive - mechanical processes. The results of studies of selected properties of grain products, affecting the intensity of the wear of materials of the handling facilities in the port grain elevator have been presented in the article, as well.

The active support of a large-scale structure, made up of two elements was designed and manufactured. The first of them - piezoelectric actuator, enables the simulations of vibrations transferred from the ground to the structure. In order to minimize vibrations transmitted through the ground to the construction, the second element of the active support - a system based on magnetorheological dampers was used. The active support enables the simulations of vibrations from the ground using a piezoelectric stack controlled in a reverse feedback loop. Control signals of the feedback loop are: the volume of deformation and vibrations in the selected structures node.

The complexity and diversity of civil engineering structures impose requirements on the monitoring systems, which are difficult to be satisfied. In the paper the concept of the distributed diagnostic system capable of monitoring the technical state of critical elements of large infrastructure objects like steel trusses, supermarket buildings, exposition halls, bridges etc. is discussed. Adaptation of such systems is essential for online assessment of technical state of the infrastructure objects and could limit the possibility of catastrophic disasters with loss of people. As a source of information data from strain gauges, passive magnetic field sensors and acceleration sensors applied to the construction are considered. For the process of selection of sensors and diagnostic methods the mathematical model of the construction and the physical test stand were used.

Enantiopure 3,6‐dihydro‐2H‐1,2‐oxazines were prepared by [3+3] cyclisations starting from lithiated methoxyallene and the L‐erythrose‐derived nitrones 1′and 3. The role of the side‐chain protective group, which steers the highly selective formation of either anti‐ or syn‐configured products, was demonstrated. A hydroboration/oxidation protocol smoothly converted 1,2‐oxazine derivative syn‐5into secondary alcohol 6. After deprotection, polyhydroxylated tetrahydro‐2H‐1,2‐oxazine 11, which can be regarded as an azasugar, was isolated. Analogous treatment of 1,2‐oxazine anti‐5with the borane not only provided the expected secondary alcohol 7, but it also induced reduction of the C=C bond and ring opening. Treatment of syn‐5and anti‐2with hydrochloric acid in methanol induced deprotections and cyclisations leading to bicyclic tetrahydro‐2H‐1,2‐oxazine derivatives. The second ring can be either a furan or a pyran ring. In the synseries, furan derivative 12was formed exclusively, and its hydrogenolysis led to enantiopure aminofuran derivative 14. Acid‐promoted rearrangement of unprotected anti‐2led to a mixture of bicyclic compounds with furan or pyran rings fused to the 1,2‐oxazine core. However, when TBDPS‐protected compound 20was used it cleanly led to 1,2‐oxazine 21with a fused furan ring and then to aminofuran 22. Alternatively, the N–O bond in unprotected anti‐2was chemoselectively reduced with samarium diiodide, efficiently generating highly functionalized allylic alcohol 23. Acid‐promoted cyclisation and deprotection furnished furan derivative 24. Mechanistic suggestions to explain the different outcomes of the acid‐induced transformations are provided. Overall, it is demonstrated that the stereodivergent addition of lithiated alkoxyallenes to L‐erythrose‐derived nitrones allow flexible access to a series of enantiopure amino polyols, including aminofuran derivatives.

A new method for the preparation of 1,4,5‐trisubstituted (imidazol‐2‐yl)acetates, based on the reaction of the corresponding imidazole 3‐oxides with dimethyl acetylenedicarboxylate (DMAD) is described. Formation of the products is rationalized by a formal 1,3‐dipolar cycloaddition and subsequent oxaloyl cleavage.

The reaction of 1,4,5-trisubstituted 1H-imidazole-3-oxides 1 with 2,2-bis(trifluoromethyl)ethene-1,1-dicarbonitrile (7, BTF) yielded the corresponding 1,3-dihydro-2H-imidazol-2-ones 10 and 2-(1,3-dihydro-2H-imidazol-2-ylidene)malononitriles 11, respectively, depending on the solvent used. In one example, a 1 : 1 complex, 12, of the 1H-imidazole 3-oxide and hexafluoroacetone hydrate was isolated as a second product. The formation of the products is explained by a stepwise 1,3-dipolar cycloaddition and subsequent fragmentation. The structures of 11d and 12 were established by X-ray crystallography.

A straightforward access to 2-unsubstituted imidazole N-oxides with subsequent deoxygenation by treatment with Raney-nickel followed by N-benzylation opens up a convenient route to lepidilines A and C. Both imidazolium salts were used to generate in situ the corresponding imidazol-2-ylidenes, which smoothly reacted with elemental sulfur, yielding imidazole-2-thiones. These reactions were performed either under classical conditions in pyridine solutions or mechanochemically using solid Cs2CO3as a base. The structure of lepidiline C was unambiguously confirmed by X-ray analysis of its hexafluorophosphate. An analogous protocol toward lepidilines B and D and their 4,5-diphenyl analogues is less efficient due to observed instability of the key precursors, i.e., the respective 2-methylimidazole N-oxides. Comparison of cytotoxic activity against HL-60 and MCF-7 cell lines of all lepidilines, as well as their selected structural analogues (e.g., 4,5-diphenyl derivatives and PF6salts), revealed slightly more potent activity of the 2-methylated series, irrespectively of the type of counterion present in the imidazolium salt. Remarkably, the well-known 1,3-diadamantylimidazolium bromide (the “Arduengo salt”), known as the precursor of the first, shelf-stable NHC representative, and its adamantyloxy analogue displayed the most significant cytotoxic activity in the studied series.