New syntheses of [1,2,5]oxadiazolo[3,4-e][1,2,3,4]tetrazine 4,6-dioxide

New methods were developed for the synthesis of [1,2,5]oxadiazolo[3,4-e][1,2,3,4]tetrazine 4,6-dioxide from 4-(tert-butyl-NNO-azoxy)-N-nitro-1,2,5-oxadiazol-3-amine or its alkali metal salts and acid anhydrides (or chlorides) in the presence of strong acids. The yield of [1,2,5]oxadiazolo[3,4-e][1,2,3,4]tetrazine 4,6-dioxide in acetic anhydride in the presence of sulfuric acid or sulfuric anhydride at 20°C in 20 min attained 83%. A general mechanism was proposed for the reactions under study. Acetyl group behaved for the first time as departing group in the synthesis 1,2,3,4-tetrazine 1,3-dioxides, and [1,2,5]oxadiazolo[3,4-e][1,2,3,4]tetrazine 4,6-dioxide was obtained in 47% yield from N-[4-(acetyl-NNO-azoxy)-1,2,5-oxadiazol-3-yl]acetamide.     

On the All-Fiber Optical Methods of the Generation and Recognition of Soliton States

Journal of Experimental and Theoretical Physics - The state of a soliton is characterized by the eigenvalues of the Zakharov–Shabat problem. The data transfer rate in the fiber-optic...     

Facile method for the synthesis of oseltamivir phosphate

A ten-step scheme for the preparation of an antiviral agent, ethyl (3R,4R,5S)-4-acetylamino-5-amino-3-(pent-3-yloxy)cyclohex-1-enecarboxylate phosphate, from (-)-shikimic acid was studied. The main parameters of the synthesis were determined and the optimal conditions for the preparation of the intermediate compounds were selected. The total yield of oseltamivir phosphate calculated based on (-)-shikimic acid was 27%.     

Debenzylation of 2,6,8,12-tetraacetyl-4,10-dibenzyl-2,4,6,8,10,12-hexaazatetracyclo[5.5.0.03,11.05,9]dodecane

The debenzylation of 2,6,8,12-tetraacetyl-4,10-dibenzyl-2,4,6,8,10,12-hexaazatetra-cyclo[5.5.0.0^3,11.0^5,9]dodecane by catalytic hydrogenolysis in a mixture of HCOOH with other RCOOH (R = Me, Et, Prⁱ) is accompanied by the N-formylation of the liberated secondary amino groups. The alkaline hydrolysis of the obtained products makes it possible to remove the formyl groups with the retention of the acetyl groups.     

Synthesis of new <Emphasis Type="Italic">N</Emphasis>-polysubstituted oxaazaisowurtzitanes by acid-catalyzed condensation of sulfonamides with glyoxal

By application of acid-catalyzed condensation of propane-2-, benzene- and methanesulfonamides with glyoxal a series of new derivatives of oxaazaisowurtzitanes were obtained, in particular, new heterocyclic systems: 2,4,6,8,12-pentaoxa-10-aza- and 2,4,8,12-tetraoxa-6,10-diazatetracyclo[5.5.0.0^3,11.0^5,9]-dodecanes.     

p-Tyrosol: a new synthetic method and new types of pharmacological activity

Russian Chemical Bulletin - A new method for the synthesis of p-tyrosol, i.e., 2-(4-hydroxyphenyl)ethanol, has been developed, which considerably simplified the process of preparation of this...     

Dynamics of frequency-modulated soliton-like pulses in a longitudinally inhomogeneous active optical waveguide

Conditions of the formation and amplification of frequency-modulated soliton-like pulses in longitudinally inhomogeneous active optical waveguides with anomalous dispersion of group velocities are studied. Group velocity dispersion profiles that are necessary for existence and amplification for active and passive optical waveguides are determined, and the dependences on the distance passed along the waveguide, duration, and chirp of the pulse are established.     

Condensation of 4-Tert-butyl-2,6-dimethylbenzenesulfonamide with Glyoxal and Reaction Features: A New Process for Symmetric and Asymmetric Aromatic Sulfones

The synthesis of substituted aza- and oxaazaisowurtzitanes via direct condensation is challenging. The selection of starting ammonia derivatives is very limited. The important step in developing alternative synthetic routes to these compounds is a detailed study on their formation process. Here, we explored an acid-catalyzed condensation between 4-tert-butyl-2,6-dimethylbenzenesulfonamide and glyoxal in aqueous H₂SO₄, aqueous acetonitrile and acetone, and established some new processes hindering the condensation. In particular, an irreversible rearrangement of the condensation intermediate was found to proceed and be accompanied by the 1,2-hydride shift and by the formation of symmetric disulfanes and sulfanes. It has been shown for the first time that aldehydes may act as a reducing agent when disulfanes are generated from aromatic sulfonamides, as is experimentally proved. The condensation between 4-tert-butyl-2,6-dimethylbenzenesulfonamide and formaldehyde resulted in 1,3,5-tris((4-(tert-butyl)-2,6-dimethylphenyl)sulfonyl)-1,3,5-triazinane. It was examined if diimine could be synthesized from 4-tert-butyl-2,6-dimethylbenzenesulfonamide and glyoxal by the most common synthetic procedures for structurally similar imines. It has been discovered for the first time that the Friedel–Crafts reaction takes place between sulfonamide and the aromatic compound. A new synthetic strategy has been suggested herein that can reduce the stages in the synthesis of in-demand organic compounds of symmetric and asymmetric aromatic sulfones via the Brønsted acid-catalyzed Friedel–Crafts reaction, starting from aromatic sulfonamides and arenes activated towards an electrophilic attack.     

A Laser Complex with a Central Wavelength of 1.55 μm for Generation of Pulses with Energy Exceeding 1 μJ and a Supercontinuum Spanning a Nearly Two-Octave Range

Optics and Spectroscopy - A fiber laser complex of telecommunication range exhibiting a block architecture the main elements of which are a pulsed erbium fiber laser and several amplification...