Synthesis of new biheterocycles containing a 1,4-benzodioxane fragment

The reaction of 1,4-benzodioxane-2-carbonyl chloride with 5-(4-aminophenyl)-1,3,4-oxa- and -thiadiazole-2-thiols afforded new biheterocyclic compounds which were converted into the corresponding S-benzyl derivatives by treatment with benzyl chloride. 5-(4-Aroylaminophenyl)-1,3,4-oxa(thia)diazole-2-thiols reacted with 2-bromomethyl-1,4-benzodioxane to give compounds in which the 1,4-benzodioxane nucleus and fivemembered heterocycle are linked through a CH₂S bridge.     

Doppler-free satellites of resonances of electromagnetically induced transparency and absorption on the D 2 lines of alkali metals

The peculiarities of intra-Doppler structures that are observed in the atomic absorption spectrum of alkali metals with the help of two independent lasers have been studied. These structures accompany ultranarrow coherent resonances of electromagnetically induced transparency and absorption. With the D ₂ line of rubidium taken as an example, it is shown that, in the scheme of unidirectional waves, the maximum number of satellite resonances caused by optical pumping selective with respect to the atomic velocity is equal to seven, while only six resonances are observed in the traditional scheme of saturated absorption with counterpropagating waves of the same frequency. The spectral position of the resonances and their polarity depend on the frequency of the saturating radiation, while their number and relative amplitude depend also on the experimental geometry. These features are of general character and should show themselves in the absorption spectrum on the D ₂ lines of all alkali metals. An explanation of these features is given. The calculated spectral separations between the resonances are compared to the experimental ones, and their possible application is discussed.     

Synthesis and some transformations of benzo-substituted 2-bromomethyl-4-methyl-2-chloro-2,3-dihydrofuro[3.2-c]-quinolines

A convenient synthetic procedure for substituted 2-bromomethyl-4-methyl-2-chloro-2,3-dihydrofuro[3.2-c]quinolines hydrobromides was developed, synthons for preparation of new substituted furoquinolines. Reactions with various nucleophiles were performed, and 2-(R’-methyl)-4-methyl-furo[3.2-c]quinolines substituted in the benzene ring were obtained.     

Two strongly contrasting Λ-systems in the <Emphasis Type="Italic">D</Emphasis> <Subscript>1</Subscript> line of <Superscript>87</Superscript>Rb in a transverse magnetic field

Four different types of spectroscopic cells that cover all possible existing versions of sealed-off cells (containing alkali atomic vapor) characterized by drastically different relaxation rates γ_rel are used to study the electromagnetically induced transparency spectra of two Λ-systems in the D₁ line of ⁸⁷Rb in the presence of transverse magnetic field. Two cw narrowband diode-lasers are used to form the coupling laser radiation (with a fixed frequency) and the probe radiation with a tunable frequency. Two strongly contrasting Λ-systems are found: the first shows resonances that are transformed from dark resonances to bright resonances in all cases apart from nanocells, whereas the second shows four dark resonances in all four different types of cell. The theoretical simulations are in good agreement with the experimental results.     

Frequency reference for atomic transitions of Rb D<Subscript>2</Subscript>-line based on the effect of selective reflection

On an example of the D₂-line of the Rb atoms the work of the frequency reference of atomic transitions is demonstrated, based on the application of the spectrum of a selective reflectance (SR) from the boundary of atom vapors with the use of nano-cell (NC) with the thickness L ~ λ/2, where λ is the laser wavelength equal to 780 nm. When changing the thickness of the nano-cell near the thickness L ~ λ/2, we observe the inversion of sign of the SR slope profile which is positive when L < λ/2 and negative when L > λ/2. In the case when the incidence angle of the laser beam on the surface of the nano-cell is close to the normal, in real-time it is possible to form the derivative of the SR which represents a resonance peak with ~35 MHz spectral linewidth and located at the atomic transition. The phenomenon of oscillation of the sign of slope while changing the nano-cell thickness from L ~ λ/2 up to L ~ 3/2λ is demonstrated. The practical application of the SR is noted.     

Interaction of nitrogen-containing propargyl compounds with CH-acids in the presence of mercury(II) acetate

Regiochemistry of the reaction of nitrogen-containing propargyl compounds with CH-acids in the presence of mercury(II) acetate has been studied. The possibility of alkylation at the substituted carbon atom of the triple bond of the nitrogen-containing propargyl compounds by sodium salts of acetylacetone and acetoacetic ester with the formation of prototropic isomers has been shown.     

Synthesis of 2-bromomethyl-4-methyl-2,3-dihydrofuro[3,2-<Emphasis Type="Italic">c</Emphasis>]-quinoline and some its transformations

Electrophilic intramolecular heterocyclization of 3-(2-chloroprop-2-en-1-yl)-2-methylquinolin-4-ol by the action of bromine gave 2-bromomethyl-2-chloro-4-methyl-2,3-dihydrofuro[3,2-c]quinoline hydrobromide which was converted into 2-hydroxymethyl-, 2-alkoxymethyl-, and 2-dialkylaminomethyl-4-methylfuro[3,2-c]quinolines by treatment with the corresponding nucleophiles.     

Synthesis of substituted 2,4-dimethylthieno[3,2-<Emphasis Type="Italic">c</Emphasis>]quinolines

A procedure was developed for the synthesis of substituted 2,4-dimethylthieno[3,2-c]quinolines via intramolecular cyclization and subsequent aromatization of 3-(2-chloroprop-2-en-1-yl)-and 3-(2-oxopropyl)-2-methylquinoline-4-thiols. The latter were obtained by alkaline hydrolysis of the corresponding thiuronium salts which were prepared in turn by reactions of 4-chloro-3-(2-chloroprop-2-en-1-yl)-and 4-chloro-3-(2-oxopropyl)-2-methylquinolines with thiourea.