Catalytic effect of nanosized metal oxides in the Biginelli reaction

The effect of nanosized metal oxides on the regio- and stereoselectivity of the multicomponent Biginelli reaction and the reaction mechanism under conditions of heterogeneous catalysis were studied. It was found that the considerable activation of reagents occurred on the surface of metal nanooxides. The Biginelli reaction occurred by two mechanisms: a carbocationic mechanism took place along with the generally accepted mechanism (through the N-acyliminium ion). Nanosized metal oxides in the presence of chiral inductors increased the regio- and stereoselectivity of the Biginelli reaction.     

Unusual heterocyclization of chalcone podands with 3-amino-1,2,4-triazole

A new type of intramolecular cyclization of 1,5-bis[2-(E-3-oxo-3-phenylprop-1-enyl)-phenoxy]-3-oxapentane with 3-aminotriazole promoted by potassium ions was discovered. A cascade mechanism for the formation of crownophane with 4,7-dihydro[1,2,4]triazolo[1,5-a]-pyrimidine fragment was suggested. Effects of oligooxyethylene fragment of the chalcone podand and acid-base catalysis on the selectivity of the cyclocondensation processes and degree of oxidation of triazolopyrimidine fragments were studied. The product structures were confirmed by IR, ¹H and ¹³C NMR spectroscopy and X-ray diffraction study.     

Pre-organization of diarylideneacetonyl crownophanes in single crystals to photochemical transformations

Specific features of crystal packings and pre-organization of diarylideneacetonyl crownophane molecules to solid-phase photochemical transformations were studied on the basis of X-ray diffraction data using methods of simulation of molecular crystal packings. The tendency of the most part of the synthesized macrocyclic E,E-isomers to the formation of homochiral crystals (P2₁2₁2₁) was revealed, while (23E,26E)-11,12,14,15-tetrahydro-8H-dinaphtho-[2,1-k:1′,2′-r][1,4,7,10]tetraoxacyclononadecine-23,26-dien-25(9H)-one is prone to polymorphism. A phenomenon of solid-phase stereospecific photochemical dimerization of molecules according to the syn-head-to-tail type without crystal destruction (single crystal—single crystal transformation) was found for one of the modifications of this crownophane.     

2,2'-Bipyridinyl carboranes as B,N,N-ligands in cyclometallated complexes of platinum(II)

Novel B,N,N-cyclometallated Pt(II) complexes of 2,2'-bipyridin-6-yl carboranes exhibit absorption and emission similar to relative Pt(II) complexes of aromatic C,N,N-ligands: the same transitions but lower intensities. DFT calculations suggest the former emits from the (3)MLCT state while for the latter the mixed (3)ICT-MLCT transitions should be considered.     

Three-dimensional diagrams of the regions occupied by induced Anger states in a multidomain magnetic medium

The regions of existence of Anger states in an iron garnet film are plotted and investigated for the first time in a space of three controlling parameters: the frequency and amplitude of the alternating field and the magnitude of the static bias field. It is shown that the dynamic spiral domains differ significantly in their configuration and properties in different regions. A quantitative parameter involving the velocity of the domain walls and the “looseness” (sparseness) of the dynamic array of magnetic domains is introduce to characterize the favorability of conditions for the formation of spiral domains. Fiz. Tverd. Tela (St. Petersburg) 40, 1865–1870 (October 1998)     

Orientation in the a minoarylation of acridine

A number of 9-aminoarylacridines were obtained by the condensation of acridine hydrochloride with various aromatic amines in the presence of sulfur. The orientation of the arylamines was established by determination of the structures of the products by alternative synthesis or measurement of the dipole moments.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 216–219, February, 1972.     

Modifications of 5,12-dihydroindolo[3,2-a]carbazole scaffold via its regioselective C2,9-formylation and C2,9-acetylation

The effective approaches for regioselective double formylation and acetylation of 5,12-dialkyl-6,7-diaryl-substituted 5,12-dihydroindolo[3,2-a]carbazoles by their treatment with dichloromethyl methyl ether in the presence of SnCl₄ or with acetyl chloride in the presence of AlCl₃ to afford the 2,9-diformyl or 2,9-diacetyl derivatives, respectively, were developed. Furthermore, new 2,9-bis(2,2-dicyanovinyl) derivatives were synthesized by the Knoevenagel condensation of diformyl-containing substrates with malononitrile, when new 2,9-bis(quinoxaline-2-yl)- and 2,9-bis(benzo[g]quinoxaline-2-yl) derivatives were formed via microwave-promoted oxidation of diacetyl-containing substrates with SeO₂ to the corresponding diglyoxals, followed by the reaction of these intermediates with o-phenylendiamine or 2,3-diaminonaphthalene, respectively. The basic optical and electrochemical properties of some 5,12-dihydroindolo[3,2-a]carbazoles were investigated.     

Preparation of 1-dichloromethyl- and 1-trichloromethylisoquinolines by a one-step reaction of 1,2,4-triazines with 1,2-dehydrobenzene

Chemistry of Heterocyclic Compounds - An original and convenient procedure has been proposed for one-step preparation of 1-dichloromethyl- and 1-trichloromethylisoquinolines in up to 40% yields via...     

Effective method for the synthesis of azolo[1,5-a]pyrimidin-7-amines

Chemistry of Heterocyclic Compounds - Condensation of aminoazoles with (2E)-(3-morpholin-4-yl)acrylonitrile and 3,3-diethoxypropionitrile was used to synthesize a series of...