New spirans containing a 1,5-benzodithiepine system, derived from methylbenzenes. Conformational transmission

[structure: see text] A synthesis of three new spirans, derived from methylbenzenes, containing the 1,5-benzodithiepine system is reported. X-ray structure proved the identity of model monospiran 9. In the solid and liquid state, the conformation of the seven-membered ring is chair, and the five-membered ring has the envelope conformation. The effect of conformational transmission in spirans 9 and 10 was observed. The synthesis of trispirans from hexamethylbenzene using the proposed scheme is also possible.     

Threshold strangeness production in pp interactions

During the actual lectures, features of the COSY-Jülich accelerator were presented, followed by a short summary of ongoing experiments at the COoler SYnchrotron COSY using internal as well as external beams in the range of 45 MeV to 2.5 GeV. Here the research of the COSY-11 collaboration is presented. This °⁰ facility studies the hidden and open strangeness production observing the ν and η′ as well the K⁺Y and K⁺K^? production in the proton—proton interactions at the respective thresholds.     

Spatial and frequency domain effects of defects in 1D photonic crystal

The aim of this paper is to present the analysis of influence of defects in 1D photonic crystal (PC) on the density of states and simultaneously spontaneous emission, in both spatial and frequency domains. In our investigations we use an analytic model of 1D PC with defects. Our analysis reveals how presence of a defect causes a defect mode to appear. We show that a defect in 1D PC has local character, being negligible in regions of PC situated far from the defected elementary cell. We also analyze the effect of multiple defects, which lead to photonic band gap splitting.     

Conformal geometry of foliations

In this article, we begin a systematic study of conformal properties of codimension-1 foliations. We first define and study local conformal invariants. A case of particular interest is that of harmonic foliations of the plane. Then we study existence of totally umbilical and “Dupin” foliations on compact 3-manifolds of constant curvature.      

Two 1-substituted 4-nitro­imidazoles

Crystalline 4-nitro-1-phenyl­imidazole, C₉H₇N₃O₂, (I), and 4′-­nitro-1-phenyl-4,1′-bii­imidazole, C₁₂H₉N₅O₂, (II), contain C—H⃛O and C—H⃛N hydrogen bonds, connecting the mol­ecules into infinite chains. The aromatic fragments in both compounds are nearly planar. The dihedral angles between the benzene and imidazole rings are 26.78 (5)° in (I) and 29.36 (8)° in (II).     

Spectroscopic study of the keto-enol equilibrium of N-aryldiacetylthioacetamides and their reactivity

An NMR study of the equilibrium between keto-enol tautomeric forms of N-aryl-diacetylthioacetamides enables us to estimate their population ratio in solvents of increasing polarity. An X-ray analysis confirmed the structure of the thermodynamically most stable tautomer. We presume that the course of heterocyclization processes with N-aryldiacetylthioacetamides is affected by the structure of the reacting tautomeric form. The treatment of N-aryldiacetylthioacetamides with oxalyl or bromoacetyl bromides leads to thiazolidine derivatives. The reactivity of the 5-methylene group in the obtained thiazolidin-4-one derivatives was investigated. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 452–459, March 2008.     

Insight into the mechanism of three component condensation leading to aminomethylenebisphosphonates

Three-component reaction of a primary amine, diethyl phosphite and triethyl orthoformate followed by acid hydrolysis of the adduct provides N-substituted aminomethylenebisphosphonic acids in good yields. Being extremely versatile, it is commonly utilized for preparation of compounds possessing potential antiosteoporotic, antibacterial, anticancer, antiparasitic or herbicidal activity. However, the mechanism of the reaction remains unknown. p-Nitroaniline has been found an interesting tool to shed light on this matter. Its use allowed to separate and identify four intermediates, both non-phosphorus and phosphorus containing, and subsequently suggest the mechanism of the whole process. The acquired knowledge was helpful in explanation the route and the final product structure obtained for more complex reaction proceeding with the use of 4-aminopyridine. Additional alkylation of the pyridine nitrogen atom, leading to unexpected N-(1-alkylpyridinium-4-amino)methylenebisphosphonic acids was unambiguously proved.