1,3-Benzothiazines (review)

Data on the methods for the synthesis of 1,3-benzothiazines and their derivatives and their chemical properties and physiological activity are correlated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 291–308, April, 1979.     

Magnetomesogens: Bis(1,3-di(4'-decoxyphenyl)propane-1,3-dionato)oxovanadium (IV)

β-Diketonate complexes of oxovanadium (IV) have been synthesized and their mesomorphic behaviour investigated. The title complex exhibits a short range monotropic columnar discotic phase, identified by its optical texture and by miscibility studies. The optical texture of the phase is retained on cooling to the crystal. As a consequence of the unpaired electron on vanadium the complexes are paramagnetic.     

Synthesis of (1,3-adamantylene)bis-1,3-dicarbonyl compounds

Reactions of 1,3-dihydroxyadamantane with 1,3-dicarbonyl compounds in the presence of 5 mol % of In(OTf)₃ afforded a series of (1,3-adamantylene)bis-1,3-dicarbonyl compounds in yields of 25–83%.     

Phosphorylated 1,3-diazoles (review)

The principal methods for obtaining and converting phosphorylated 1,3-diazoles, including³²P-labeled compounds and compounds that contain spin labels, and their use in organic synthesis, molecular biology, bioorganic chemistry, medicine, and agriculture are examined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 723–740, June, 1990.     

Triplet 1,3-diphenylpropynylidene (Ph-C-C-C-Ph)

Photolysis (lambda>571 nm) of 1,3-diphenyldiazopropyne (9) affords triplet 1,3-diphenylpropynylidene (3), as characterized by IR, UV/vis, and EPR spectroscopy in low-temperature matrices. Two conformational isomers of triplet 3 are spectroscopically distinguishable. The initially formed, non-relaxed conformer is believed to reflect the geometry of the diazo precursor, as enforced by the rigid matrix. Annealing the matrix permits the structure to relax to the equilibrium D2d geometry. The highly symmetric equilibrium structure of 3 is best envisioned as a 1,3-allenic diradical. Density functional theory calculations suggest that the equilibrium structure does not exhibit a bond-localized structure that would be characteristic of an acetylenic carbene. Chemical trapping with O2, however, affords products that are familiar as carbene trapping products: carbonyl oxide 10, ketone 11, and dioxirane 12. Irradiation (lambda>261 nm) of triplet 1,3-diphenylpropynylidene (3) results in cyclization to singlet diphenylcyclopropenylidene (6), a process that is photochemically reversible at lambda=232 nm. Diphenyl-1,2-propadienylidene (7) was not observed under any irradiation conditions.     

Electronic structure of solid state tris(1,3-diphenyl-1,3-propanedionato)aquoeuropium(III)

Single crystal orthoaxial absorption spectra are reported for tris(1,3-diphenyl-1,2-propanedionato)aquoeuropium(III) at ambient temperature and 77 K. The hypersensitive ⁷F_o→⁵D₂ and magnetic/electric dipole forbidden ⁷F_o→⁵D_o transitions are found to be unusually intense. Polarizations and absolute oscillator strengths are determined for all observed transitions from the ground state at 77 K.     

1,3-Bis(triphenylphosphonium-ylidyl)cyclotetraphosphane

1,3-Bis(triphenylphosphonium-ylidyl)cyclotetraphosphines The title compounds 3a , b result from the condensation of the ylidyldichlorophosphines Ph₃PCR? PCl₂ 1a , b (R = Me, 3-Tol) with phenyl bis(trimethylsilyl)phosphine 2 . Analysis of the ³¹P-NMR spectra and the X-ray structure investigation of 3a demonstrate a folding of the four-membered ring and an all-trans orientation of the substituents.     

N-(1,3-Thiazol-5(4H)-yliden)amine aus 1,3-dipolaren Cycloadditionen von Aziden mit 1,3-Thiazol-5(4H)-thionen

N-(1,3-Thiazol-5(4H)-ylidene)amines via 1,3-Dipolar Cycloaddition of Azides and 1,3-Thiazol-5(4H)-thiones Organic azides 5 and 4,4-dimethyl-2-phenyl-1,3-thiazol-5(4H)-thione ( 2 ) in toluene at 90° react to give the corresponding N-(1,3-thiazol-5(4H)-ylidene)amines (= 1,3-thiazol-5(4H)-imines) 6 in good yield (Table). A reaction mechanism for the formation of these scarcely investigated thiazole derivatives is formulated in Scheme 3: 1,3-Dipolar azide cycloaddition onto the C?S group of 2 leads to the 1:1 adduct C . Successive elimination of N₂ and S yields 6 , probably via an intermediate thiaziridine E .     

(1E)-1,3-dimethoxy-1,3-butadiene

Reaction of 1,1-dimethoxy-2-butyne (II) with sodium methoxide in dimethyl sulfoxide at 100° yields (1E)-1,3-dimethoxybutadiene (III) (20–30%). The diene III undergoes ready Diels-Alder reaction with maleic anhydride, N-phenyltriazolinedione and dimethyl acetylenedicarboxylate.     

The crystal and molecular structure of BIS(1,3-diphenylpropane-1,3-dionato)-Di-n-butyltin(IV)

The crystal and molecular structure of bis(1,3-diphenylpropane-1,3-dianoto)di-n-butyltin(IV) has been determined from three-dimensional X-ray data by the heavy-atom method. The space group is P2₁/n. Unit cell constants are a 1117.56(30), b 857.87(16), c 1758.36(51) pm, and β 99.398(20)°. The observed density of the yellow crystals (m.p. 92–94°C) is 1.38 g ml⁻³ and requires two molecules per unit cell. The molecule has a center of symmetry. Refinement converged to give final discrepancy indices, R = 0.0481, R_w = 0.0607; and goodness-of-fit (GOF) was 3.216 for 1688 observed reflections. The molecular skeleton about tin is a slightly distorted octahedron with bond distances: SnC, 212 pm; and SnO, 219 and 220 pm. The O(1)SnO(2) bond angle is 83.8°, and CSnO bond angles are very nearly 90°. The structural parameters are compared with those of other organotin complexes of similar stoichometry.