Synthesis of 4- and 5-(s-triazolo[4,3-b]pyridazinyl-3)-substituted cyclic polyols

4( R )-(6-Chloro-s-triazolo[4,3-b]pyridazinyl-3)-1,4-furanoses 10 and 11 , 5( R )-(6-chloro-s-triazolo[4,3-b]pyridazinyl-3)-1,5-pyranose 13 , and 2(S),3( R )-dihydro-5-(6-chloro-s-triazolo[4,3-b]pyridazinyl-3)-2,3-O-isopropylidenefuran ( 12 ) were prepared by cyclization of hydrazones 6–9 obtained from 6-chloro-3-hydrazinopyridazine ( 1 ) and aldofuranoses 2, 3 and 4 , and aldopyranose 5 .     

Nucleophilic addition to benzo[b]thieno[2,3-b]benzo[b]thiophene S,S,S′,S′-tetroxide

The reaction of benzo[b]thieno[2,3-b]benzo[b]thiophene S,S,S′,S′-tetroxide with primary and secondary amines and with alcohols gave 10 b-amino- and 10 b-alkoxy-5a, 10b-dihydro-benzo[b]thieno[2,3-b]benzo[b]thiophene S,S,S′,S′-tetroxides. These nucleophilic reagents do not add to benzo[b]thieno[2,3-b]benzo[b]thiophene S,S-dioxide.     

Invariant subspaces for a class of complete Pick kernels

Motivated by the work of McCullough and Trent, we investigate the -invariant subspaces of the Hilbert function spaces associated to the Szego kernels on the open unit disk. In particular, we characterize those kernels for which the the -invariant subspaces are hyperinvariant, and (partially) those for which the so-called BLH subspaces are cyclic, obtaining counterexamples to two questions posed by McCullough and Trent.

     

Acid dissociation constants of some nitrogen-containing multinuclear systems

The pK_a values have been determined spectrometrically of the 5, 8, 8-trimethyl-2, 4, 6-trioxo-1, 2, 3, 4, 5, 6, 7, 8, 9, 10-decahydropyrimido[4, 5-b]quinolines Ia–Ic, the 5, 8, 8-trimethyl-2, 4, 6-trioxo-1, 2, 3, 4, 6, 7, 8 9-octahydropyrimido [4, 5-b]quinolines IIa and IIb, the 2, 4, 6-trioxo-5-phenyl-1, 2, 3, 4, 5, 11-hexahydro-11-azapyrimido [4, 5-b]fluorenes IIIa–IIIc, and the 4-amino uracils IVa–IVc. The following sequences of the dissociation of the protons attached to the nitrogen atoms have been established: for I, N₍₁₎ > N₍₁₀₎ > N₍₃₎; for II, N₍₁₎ > N₍₃₎; for III, N₍₁₁₎ > N₍₁₎ > N₍₃₎; and for IV, N₍₃₎ > N₍₁₎.     

Experimental Evidence of Intramolecular CAr–H···O=C Hydrogen Bonds in the Structure of (Diaryl)tetrahydrofuranones Using Spectroscopic Tools

The occurrence of bifurcate H‐bonds C_Ar–H···O=C in the structure of (diaryl)‐tetrahydrofuranones was experimentally demonstrated using different methods and techniques. The consistent increasing spin–spin coupling constants ¹J(C,H) of the ortho‐H‐atoms and low‐field shift of v_C=O in IR spectra of 2,2‐(diaryl)tetrahydrofuran‐3(2H)‐ones relative to their 5,5‐diaryl counterparts, as well as pronounced dependence of the ortho‐C–H H‐atoms chemical shifts on the temperature and solvent polarity along with X‐ray diffraction analysis data unambiguously point to the existence of weak C_Ar–H···O=C H‐bonds in these molecules.     

Synthesis,structure and biological activity of new 6,6‐dimethyl‐2‐oxo‐4‐{2‐[5‐organylsilyl(germyl)]furan(thiophen)‐2‐yl}vinyl‐5,6‐dihydro‐2H‐pyran‐3‐carbonitriles

New 6,6‐dimethyl‐2‐oxo‐4‐{2‐[5‐alkylsilyl(germyl)]furan(thiophen)‐2‐yl}vinyl‐5,6‐dihydro‐2H‐pyran‐3‐carbonitriles (IC₅₀: 1–6 µg ml^?1) have been prepared by the condensation of corresponding silicon‐ and germanium‐containing furyl(thienyl)‐2‐carbaldehydes with 3‐cyano‐4,6,6‐trimethyl‐5,6‐dihydropyran‐2‐one using piperidine acetate as a catalyst. The obtained carbonitriles were identified using NMR (¹H, ¹³C and ²⁹Si) spectroscopy and GC‐MS. The structure of 6,6‐dimethyl‐2‐oxo‐4‐[2‐(5‐trimethylsilyl)thiophen‐2‐yl]‐5,6‐dihydro‐2H‐pyran‐3‐carbonitrile was studied using X‐ray diffractometry. The influences of the heterocycle and the structure of the organoelement substituent on cytotoxicity and on matrix metalloproteinase inhibition have been studied. Copyright © 2015 John Wiley & Sons, Ltd.     

Synthesis,structure and cytotoxicity of new 2‐[(3‐aminopropyl)dimethylsilyl]‐5‐furfural diethylacetals and 2‐[(3‐aminopropyl)dimethylsilyl]‐5‐phenylfurans

Novel 2‐[(3‐aminopropyl)dimethylsilyl]‐5‐furfural diethylacetals and 2‐[(3‐aminopropyl)di‐methylsilyl]‐5‐phenylfurans have been synthesized by a hydrosilylation reaction of aliphatic and heterocyclic N‐allylamines in the presence of the Speier's catalyst. The effects of the structure of the amine and nature of organic substituent at the furan ring on the cytotoxicity of the new compounds have been studied. Copyright © 2013 John Wiley & Sons, Ltd.     

The Fredholm Index for Elements of Toeplitz-Composition C<Superscript>*</Superscript>-Algebras

We analyze the essential sectrum and index theory of elements of Toeplitz-composition C^*-algebras (algebras generated by the Toeplitz algebra and a single linear-fractional composition operator, acting on the Hardy space of the unit disk). For automorphic composition operators we show that the quotient of the Toeplitz-composition algebra by the compacts is isomorphic to the crossed product C^*-algebra for the action of the symbol on the boundary circle. Using this result we obtain sufficient conditions for polynomial elements of the algebra to be Fredholm, by analyzing the spectrum of elements of the crossed product. We also obtain an integral formula for the Fredholm index in terms of a generalized Chern character. Finally we prove an index formula for the case of the non-parabolic, non-automorphic linear fractional maps studied by Kriete, MacCluer and Moorhouse.     

Synthesis and cytotoxicity of silylalkylthio‐substituted N‐heterocycles and their hydroselenites

New hydroselenites of the different silylalkylthio‐substituted N‐heterocycles have been prepared by the reaction of selenium dioxide with N‐heterocycles in an aqueous medium. Their structure was confirmed by ¹H, ¹³C, and ⁷⁷Se NMR data. Most of these silylalkylthio‐substituted N‐heterocycles and their hydroselenites have an expressed cytotoxic activity on the MG‐22A (mouse hepatoma), HT‐1080 (human fibrosarcoma), B16 (mouse melanoma), and Neuro 2A (mouse neuroblastoma) cell lines. Some of the hydroselenites exhibit free‐radical protection simultaneously with a high cytotoxic effect. The substances studied were also active in vivoagainst sarcoma S‐180. Copyright © 2003 John Wiley & Sons, Ltd.     

1-(Heteryloxy)silatranes

Novel heterocyclic 1-derivatives of silatranes have been obtained. The optimal, synthetic method for the indicated compounds is transesterification of tetraethoxysilane by an equimolar mixture of triethanolamine and a heterocyclic (or aromatic) hydroxyl-containing compound.Dedicated to the 100th anniversary of the birth of Academician A. N. Nesmeyanov.Latvian Institute of Organic Synthesis, Riga LV-1006, Latvia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1203–1206, September, 1999.