A three-components regioselective synthesis of 3-[2-formamidovinyl(phenyl)amino]-acrylic acid based on an opening of the imidazole ring under the influence of acetylene carboxylic acids esters or cyanophenylacetylene in aqueous acetonitrile in up to 86

Pyroxene is one of the indicator minerals of kimberlites, the compositional features of which are used to study the petrogenetic and mineragenic parameters of deep diamond formation - RT conditions of the diamond-generating mantle and its composition, in particular, indicator parasteresis of diamond satellite minerals. It occurs both in inclusions of mantle xenoliths and as porphyry phenocrysts in kimberlites. Microprobe analysis (JSM 6510 LA/JET-2200) of pyroxene compositions from eclogite xenoliths of the Katoka pipe (95 grains) and from kimberlites of the Katoka, Luele, Lx071 diamond pipes (800 grains) was carried out. The data obtained made it possible to compare the composition of pyroxenes in terms of main and minor elements and to establish signs of similarity and differences between two different genetic groups of this indicator mineral of kimberlites, as well as to identify its chemical-genetic groups (ChGG) indicator for diamonds.

The reaction of 1-methylisoquinoline with ethyl esters of 1-aryl-2-oxalylacetylenes occurs under mild conditions (20–25 °C, without a catalyst) to selectively afford functionalized oxazino[2,3- a ]isoquinolines with a yield of up to 88%.

One-pot chemo-, regio- and stereoselective synthesis of ( Z )- N -acylethenyl-4-( E )-[( Z )-acylethenyl]iminodihydroquinolines with high yields (66-98%) has been elaborated by the reaction between 4-aminoqiunoline and alkynones in the КОН/H2O/MeCN system.

The article reports new data on previously undescribed lamellar-like (linearly oriented) structures in clinopyroxenes from mantle xenoliths of garnet pyroxenites (Obnazhennaya pipe, Northern Siberia). The origin and mineral diversity of lamellar structures in xenoliths from the Obnazhennaya pipe are supposed to be related to a breakdown of solid solutions during a decrease of P–T parameters. Our study shows that metasomatic recrystallization of initial clinopyroxene with linear exsolution structures leads to the formation of new secondary mineral assemblages. The secondary clinopyroxene reproduces (inherits) framework with linearly oriented inclusions, which are morphologically similar to the primary exsolution structures. Thus, the pyroxenite xenoliths from the Obnazhennaya pipe contain two generations of mineral associations with lamellar structures: primary and secondary. The primary association is composed of diopside, containing lamellae of enstatite, pyrope, spinel and rutile. The secondary (metasomatic) clinopyroxene contains half as much Al2O3 (3.4 wt %) and Na2O (1.7 wt %) and is enriched in MgO and CaO compared to the primary clinopyroxene. Nevertheless, the chemical composition of the secondary pyroxene still corresponds to diopside end-member. The metasomatic association comprises aligned pargasite (Al-rich amphibole) instead of orthopyroxene (enstatite) lamellae, and the secondary rutile is enriched in chromium (up to 3.1 wt % Cr2O3) in contrast to rutile from the primary mineral assemblage.

Acridine has been found to undergo readily concurrent N(1)- and С(9)-functionalization under the action of ethyl aryl-2-oxobut-3-ynoates and water to form pharmacologically promising previously unknown N-alkenylacridones in 80–84

Xenoliths of high-alumina pyroxenites in the Quaternary basalts of the Sigurd Volcano of West Spitsbergen are spinel and spinel-garnet clinopyroxenites, spinel-garnet websterites, and websterites. The granoblastic texture with relics of subhedral magmatic texture, the change of mineral assemblages, and the signs of partial melting in the xenoliths reflect their multistage formation. The goal of our study was to determine the sequence and thermodynamic conditions of the change of mineral assemblages and to establish their age by Re-Os, U-Pb, Sm-Nd, and Rb-Sr isotope dating. It has been established that the primary assemblage in the pyroxenites, which included high-alumina Opx, Cpx, and Spl, was transformed in several stages: (1) Spl -> Grt replacement with the formation of garnet-containing websterites and clinopyroxenites, (2) development of kelyphitic Opx-Spl rims over Grt grains, (3) formation of Amph, (4) exsolution with the formation of Cpx and Opx, and (5) partial melting. Comparison of the obtained results with published data shows that the primary assemblage is similar in Al2O3/MgO ratio to Opx + Cpx +/- Spl cumulates resulted from the crystallization of basaltic melts at 1.2 GPa and the degree of crystallization of similar to 15%, i.e., in the lower crust (at 2.0 GPa, Grt and Cpx crystallize from the solution). The equilibrium parameters of the Grt-Opx assemblage in the pyroxenites are 1060-1310 degrees C and 2.2-3.3 GPa; in the P-T diagram, their points are localized below the Spl -> Grt phase transition curve, in the system CaO-MgO-Al2O3-SiO2, thus corresponding to the model continental geotherm with a surface heat flow density of 60 mV/m(2) and somewhat higher. This indicates the Spl -> Grt replacement and the formation of garnet-containing pyroxenites in the shallow-depth upper mantle. The formation of kelyphitic Opx-Spl rims over the Grt grains indicates a subsequent temperature and pressure decrease to values above the Grt -> Spl phase transition curve. This is confirmed by the presence of exsolution structures in pyroxene, which formed when the temperature decreased by 100-150 degrees C. The Re and Os isotope composition in the bulk samples of Spl-Grt websterites that did not undergo partial melting corresponds to an age of 457.0 +/- 3.5 Ma, which reflects the time of transformation of the primary Cpx-Opx-Spl assemblage into a garnet-including one. A similar value (488.6 +/- 5.9 Ma) was obtained by U-Pb dating of zircon from Spl-Grt websterite, also without signs of melting. Zircon crystals from Spl-Grt clinopyroxenite with clear signs of partial melting have typomorphic features of autochthonous magmatic zircons. They form a single age cluster of 310.7 +/- 3.3 Ma, which marks the age of melt crystallization in the pyroxenites. Thus, Spl pyroxenites are, most likely, Opx + Cpx +/- Spl cumulates, products of crystallization of basaltic melts in the lower crust. The subsequent Spl -> Grt replacement and the formation of garnet-containing websterites and clinopyroxenites in the shallow-depth upper mantle can be regarded as an indicator of the delamination of the continental crust into the mantle, and the Re-Os isochron date of 457.0 +/- 3.5 Ma is the most likely upper age bound of the crust delamination into the mantle. The subsequent uplifting of the Spitsbergen lithosphere, which was expressed as the formation of kelyphitic Opx-Spl rims over garnet, exsolution in pyroxene, and partial melting, was not far in time from the delamination stage and lasted < 300 Ma.

Abstract—The analysis of Nb–Zr–Y systematics and thermal regimes of lithospheric mantle of the Siberian, Kaapvaal, North American, North China, and South China cratons indicates their belonging to two types, one comprising the first three cratons (Siberian, Kaapvaal, and North American) (SKNA) and the other including the last two cratons (NCSC). Peridotites in the mantle of SKNA cratons have a Paleoarchaean age and are characterized by Nb content up to 5–6 ppm which is higher than in the primitive mantle (PM). The Zr and Y content in these peridotites is lower than in PM and, in a significant part of the samples, lower than in CI chondrite; these peridotites have superchondrite Nb/Y ratios (>1.0) and chondrite to superchondrite Zr/Y ratios. Thermal regimes in the mantle of SKNA cratons correspond to the model geotherm with surface heat flux density of 45 mW/m2 and fall in the diamond stability region; they are characterized by low (24.4 to 25.1°C/kb) quasi-thermal gradients (TG) reflecting the change in temperature with pressure increasing by 1 kb. The mantle peridotites of the North China Craton have a predominantly lower Nb content than in PM whereas the Nb content in the South China craton peridotites is somewhat higher than in PM. The Nb/Y ratios (ranging from subchondritic to superchondritic but remaining below 1.0) and the Zr/Y ratios (mainly subchondritic) correspond to those in peridotites of the ophiolite complexes of the South Urals and Northern Tibet. The thermal regimes in the mantle of the North China and South China cratons are characterized by the geotherms close to the model ones with heat flux densities of 55 and 60 mW/m2, respectively, and high average TG ​​(36.7 ± 0.5 and 41.3 ± 1.3°C/kb); these regimes correspond to the graphite stability region. The depth of the petrological boundary between the lithosphere and asthenosphere (lithosphere–asthenoasphere boundary, LAB) in the mantle of the SKNA cratons was ~200 km in the Paleoarchaean and, with the allowance for the geophysical data, has remained at the same level up to present. In the mantle of the North China and South China cratons as well as in the Baikal rift (Central Asian folded belt) and epi-Grenville Svalbard platform, since the end of the Paleoarchaean this boundary has been regularly rising to at least 70–80 km in Late Proterozoic. The difference of the mantle underlying the SKNA and NCSC cratons in terms of Nb–Zr–Y systematics and thermal regimes indicates the existence of different domains in the lithosphere since the end of the Paleoarchaean. The mantle of the first type of cratons is probably the relics of chondrite material that has not been completely reworked by melting and fractionation of the Fe-group elements and Nb with close properties. The mantle of the second type of cratons has geochemical features peculiar to PM.

Mantle xenoliths were found in alkaline basalts of Tokinsky Stanovik (TSt) in the Dzhugdzhur-Stanovoy superterrane (DS) and Vitim plateau (VP) in the Barguzin–Vitim superterrane (BV) (Stanovoy suture area) at junction of the Central Asian Orogenic Belt (CAOB) and the Siberian craton (SC). Xenoliths from TSt basalts are represented by spinel lherzolites, harzburgites, wehrlites; while VP basalts frequently contain spinel–garnet and garnet peridotites lherzolites, and pyroxenites. Xenoliths in kimberlites of the Siberian craton are mainly represented by garnet-bearing lherzolites with abundant eclogite xenoliths (age of 2.7–3.1 Ga), which were not found in mantle of superterranes. The Re-Os determinations point to the Early Archean age of peridotites and eclogites from mantle beneath the Siberian craton. The major and trace (rare-earth and high-filed strength) elements and Nd-Sr-Os composition were analyzed in the peridotites (predominant rocks) of lithospheric mantle at junction of the Central Asian Orogenic Belt and Siberian Craton. The degree of rock depletion in CaO and Al2O3 and enrichment in MgO relative to the primitive mantle in the peridotites of the Dzhugdzhur–Stanovoy superterrane is close to that of the Siberian craton. The peridotites of the Barguzin–Vitim superterrane are characterized by much lower degree of depletion and have mainly a primitive composition. Mantle melting degree reaches up to 45–50% in the Siberian Craton and Dzhugdzhur-Stanovoy superterrane, and is less than 25% in the Barguzin–Vitim terrane. The mantle peridotites of the craton as compared to those of adjacent superterranes are enriched in Ba, Rb, Th, Nb, and Ta and depleted in Y and REE from Sm to Lu. However, all studied peridotites are characterized by mainly superchondritic values of Nb/Ta (>17.4), Zr/Hf (>36.1), Nb/Y (>0.158), and Zr/Y (>2.474). The Nb/Y ratio is predominantly >1.0 in SC peridotites and < 1.0 in the superterrane peridotites. The Nd and Sr isotopic compositions in the latter correspond to those of oceanic basalts. The 187Os/188Os ratio is low (0.108–0.115) in the peridotites of the Siberian Craton and > 0.115 but usually lower than 0.1296 (primitive upper mantle value) in the peridotites of the Dzhugdzhur–Stanovoy and Barguzin–Vitim superterranes. Thus, the geochemical and isotopic composition of peridotites indicates different compositions and types of mantle beneath the Siberian craton and adjacent superterranes of the Central Asian Orogenic Belt in the Early Archean, prior to the formation of 2.7–3.1 Ga eclogites in the cratonic mantle.

The analysis of author's and literary data on concentrations of Nb, Ta, Zr and Hf and on Nb/Ta and Zr/Hf relations in eclogite and peridotite xenoliths from a subcontinental lithospheric mantle (SCLM) beneath Pcm cratons allowed us to establish the following: (1) Xenoliths of mantle peridotites from the kimberlites of Kaapvaal, North American and Siberian cratons (temperature from 900-1000 to 1350-1400 degrees C, pressure from 1.5-2.0 to 5-6 GPa, Delta logfO(2)(FMQ) from -5 to -3) are enriched with Nb and Ta relative to chondrite CI and primitive mantle PM, whereas peridotites from the mantle of the North China craton are close to CI in their content or depleted in comparison to it; (2) Despite significant fluctuations, superhondritic values of Nb/Ta (> 17.4) and Zr/Hf (> 36.0) are characteristic of most peridotite xenoliths from the subcratonic mantle, with the exception of North China craton mantle xenoliths, where they are close to or below CI; (3) In the xenoliths of eclogites from the mantle of the Kasai, Man, Slave cratons (temperature from 900-1000 to 1400-1500 degrees C, pressure from 3 to 5-6 GPa), the content of Nb is 2-3 orders of magnitude higher than those in CI and PM, and the ratio of Nb/Ta ranges from chondritic to superchondritic values. The results of the analysis thus indicate that the SCLM zones, corresponding to the area of diamond stability, are one of the tanks in BSE with superchondritic Nb/Ta and Zr/Hf values.

The origin of spinel-garnet pyroxenite from xenoliths in Quaternary basaltoids of Spitsbergen Island (Svalbard Archipelago) is discussed. The rocks have a high concentration of Al2O3 and MgO and low Cr. The primary magmatic association Spl-Opx-Cpx and the high Al content in pyroxenes provide evidence for the formation of these rocks as cumulates of hydrous basaltic melts in the lower crust at a pressure of ~1.2 GPa. Transformation of the texture from the magmatic hypidiomorphic to the metamorphic granoblastic and growth of garnet at the expense of spinel and high-alumina pyroxenes indicate transport of rocks to a depth below the spinel/garnet phase transition boundary in the Cr2O3-free CaO-MgO-Al2O3-SiO2 system. The parameters of the Grt-Opx equilibrium range within 1060-1120 °C and 2.2-2.6 GPa. Thus, magmatic pyroxenite was transported to a great depth into the mantle, which provides evidence for delamination in the region of the lower continental crust containing ultramafic cumulates.

Using IR–Fourier spectrometry (FTIR) and simultaneous thermal analysis combined with quadrupole mass spectrometry of thermal decomposition products (STA + QMS), olivines and clinopyroxene from xenolites of spinel and garnet lherzolites contained in kimberlites and alkaline basalts were studied to confirm the occurrence of hydrogen and carbon within the structure of the minerals, as well as to specify the forms of H and C. The presence of hydroxyl ions (OH–) and molecules of crystal hydrate water (H2Ocryst) along with CO2, CH, CH2, and CH3 groups was detected, which remained within the structures of mantle minerals up to 1300°C (by the data of both techniques). The total water (OH–and H2Ocryst) was the prevailing component of the C–O–H system.

Metal-free reaction between quinolines, aryltrifluoroacetylacetylenes and water at -18 °C-rt in MeCN resulted in stereoselective assembly of trifluoromethylated oxazinoquinolines with up to 99% yield that was essentially in contrast to a similar reaction with pyridines. The annulation proceeded via the 1,3-dipolar adducts of quinolines with trifluoroacetylacetylenes followed by intramolecular cyclization involving the trifluoroacetyl group and a molecule of water.

According to X-ray diffraction data, crystalline 3-(benzoxazol-2-ylthio)-3-phenyl-2-propenonitrile is a substantially nonplanar Z-isomer. The resulting single crystal has layered structure as a result of π – π stacking. 1 H NMR data testify small amounts of E -isomer in the samples dissolved in chloroform.

Metal- and solvent-free reaction of quinolines with two molecules of aryltrifluoroacetylacetylenes afforded 3-arylethynyl-3-trifluoromethyl-1,3-oxazinoquinolines in up to 92% yields. The formation of a zwitterionic intermediate in the first step triggered a multistep domino reaction. This one-pot synthesis opens an easy access to novel quinoline derivatives bearing trifluoromethyl, acetylene and ketone functions, thus providing a powerful tool for drug design.