Reactions at the double bond in the epoxy group of arglabin

The interaction of arglabin, a sesquiterpene lactone of the guainane type, with peracetic acid and hydrogen chloride has been investigated. This led to the synthesis of nine compounds the structure of which have been established in the basis of spectral characteristics (IR, PMR, and mass spectra). The structures and absolute configurations of the molecules of 3,10-dichloro-1,4-dihydroxy-and 10-chloro-1-hydroxy-3,4-epoxyarglabins have been determined as 3R, 10R-dichloro-1R,4R-dihydroxy-5S,6S,7S-trans-trans-guai-11(13)-en-6,12-olide and 10R-chloro-1R-hydroxy-3S,4R-epoxy-5S,6S,7S-trans-trans-guai-11(13)-en-6,12-olide, respectively.Institute of Organic Synthesis and Coal Chemistry, Academy of Sciences of the Kazakh SSR, Karaganda. A. N. Nesmeyanov Institute of Organometallic Compounds, Academy of Sciences of the USSR, Moscow. Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR, Novosibirsk. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 33–42, January–February, 1991.     

Synthesis of ephedrine (dialkyl phosphorothioate)s. Crystallographic structure of ephedrine (diethyl phosphorothioate)

The synthesis of ephedrine (dialkyl phosphorothioate)s has been effected. The method of their preparation and their properties are described. The IR and PMR spectra of ephedrine (dialkyl phosphorothioate)s and some results of an x-ray structural investigation of the spatial structure of ephedrine (diethyl phosphorothioate) are given.Institute of Organic Synthesis and Coal Chemistry, Kazakh SSR Academy of Sciences, Karaganda. A. N. Nesmeyanov Institute of Heteroorganic Compounds, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 88–91, January–February, 1989.     

Conformation of the rings and relative stabilities of isomers of trans,trans- and trans,cis-eudesm-6,12-olides

An investigation has been made by the method of molecular mechanics of a number of isomers of trans,trans- and trans,cis-eudesm-6,12-olides. Questions of the energetic advantageousness of particular isomers, the influence of the orientation of the substituents in the mechanism on their conformation, and the relative stability of the conformers with different methods of linking the rings are considered.A. M. Nesmeyanov Institute of Organometallic Compounds, USSR Academy of Sciences, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 193–197, March–April, 1990.     

Conformations of the rings and relative stabilities of isomers of trans,trans- and trans,cis-eudesman-8,12-olides

A series of isomers of trans,trans- and trans,cis-eudesman-8,12-olides has been investigated by the method of molecular mechanics (MMM). Questions of the energetic suitability of particular isomers, of the influence of the orientation of substituents attached to the basic skeleton on their conformation, and of the relative stabilities of the conformers with different methods of linking the rings are considered.A. N. Nesmeyanov Institute of Heteroorganic Compounds, USSR Academy of Sciences, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 334–338, May–June, 1990.     

Molecular structure of 4,15-dibromo[2.2]paracyclophane

An x-ray structural study has shown that the nature of the steric distortions in [2,2]paracyclophane remains practically unchanged when Br-substituents are introduced into positions 4 and 15.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 588–590, March, 1990.     

Crystal structure of the La3+ sandwich complex based on 8-membered macrocyclic siloxanolate ligands

The product of the reaction between anhydrous lanthanum trichloride and potassium vinylsiloxanolate, K₅[VinSiO₂]₈La₄(₄-OH)[O₂SiVin]₈ · 5n-BuOH·2H₂O has been studied by X-ray diffraction. The compound is a «sandwich»-type complex where macrocyclic vinyloctasiloxanolate ligands with regularcis-configuration have co-axial and antiparallel orientation. These ligands coordinate a planar «cationic layer» formed by four La³⁺ ions and stabilized by an additional ₄-OH^– bridge ligand. A three-dimensional cage structure of complex lanthansiloxanolate pentaanions linked through the coordinated K⁺ counter-ions is formed in the crystal studied.Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 184–189, January, 1993.     

The charge-transfer motif in crystal engineering. Self-assembly of acentric (diamondoid) networks from halide salts and carbon tetrabromide as electron-donor/acceptor synthons

Unusual strength and directionality for the charge-transfer motif (established in solution) are shown to carry over into the solid state by the facile synthesis of a series of robust crystals of the [1:1] donor/acceptor complexes of carbon tetrabromide with the electron-rich halide anions (chloride, bromide, and iodide). X-ray crystallographic analyses identify the consistent formation of diamondoid networks, the dimensionality of which is dictated by the size of the tetraalkylammonium counterion. For the tetraethylammonium bromide/carbon tetrabromide dyad, the three-dimensional (diamondoid) network consists of donor (bromide) and acceptor (CBr(4)) nodes alternately populated to result in the effective annihilation of centers of symmetry in agreement with the sphaleroid structural subclass. Such inherently acentric networks exhibit intensive nonlinear optical properties in which the second harmonics generation in the extended charge-transfer system is augmented by the effective electronic (HOMO-LUMO) coupling between contiguous CBr(4)/halide centers.     

Aminals in the synthesis of 1,3-substituted propargylamines and 3H-2-vinylidene-3-aminobenzofuran derivatives

Aminals of aromatico-hydroxyaldehydes react when heated with terminal acetylenes to form, depending on the reaction conditions and the nature of the starting compounds, 1,3-substituted propargylamines or 3H-2-vinylidene-3-aminobenzofuran derivatives, the structures of which were established by X-ray diffraction.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 455–460, March, 1994.     

Synthesis and properties of 2-(3,5-di-tert-butyl-4-hydroxyphenyl)-5-nitroindazole

N-(2-Azido-5-nitrobenzylidene)-3,5-di-tert-butyl-4-hydroxyaniline (3a) and N-(2-azido-5-nitrobenzilidene) aniline (3b), when heated in dimethylformamide yielded 2-(3,5-di-tert-butyl-4-hydroxyphenyl)-5-nitroindazole (4a) and 2-phenyl-5-nitroindazole (4b), respectively. The structure of4b was confirmed by X-ray analysis. A stable phenoxyl radical was shown to originate from the oxidation of4a with lead (IV) dioxide.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1095–1097, June, 1994.