Showing papers on "Triazene published in 2003"

Copper-Assisted Arylation of 1-Thiosugars: Efficient Route to Triazene Substituted Arylthioglycosides

Abstract: Efficient copper mediated arylation of sugar thiols by o-haloaryl triazenes under mild conditions is described. The developed method allows the preparation of symmetrical and unsymmetrical 1,3-bis(glycopyranosylthio)benzene derivatives.

Synthesis and properties of new polyurethane ionomers. I. Photosensitive cationomers with triazene units

Abstract: New bifunctional triazene compounds 1-(m- hydroxymethyl)phenyl-3-(2-hydroxyethyl)-3-methyltriaz(1)ene and l-p-nitrophenyl-3,3-di(2-hydroxyethyl)triaz(1)ene as intermediates in polyurethane synthesis were prepared. Photosensitive polyetherurethane cationomers based on poly(tetramethylene oxide) diol of 2,000 average molecular weight, tolylene-2,4-diisocyanate, and N-methyldiethanolamine/triazene diols, as cochain extender, followed by a quaternization with benzyl chloride, were synthesized and characterized. Upon UV irradiation, feniltriazene chromophore in monomer and both polymers (ionomeric or nonionomeric type) is irreversibly cleaved, as evidenced in photolytic and kinetic studies. The rate constant of photolysis in ionomer film was lower than for the corresponding nonionic film. A positive pattern can then be developed by treatment with CHCl3 that dissolves the exposed zone, while the unexposed area remains resistant and insoluble. By incorporating side nitrofeniltriazene groups, photostable polyurethanes were obtained. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1203–1210, 2003

Method for estimating decomposition characteristics of energetic chemicals

Abstract: Experimental data on the decomposition characteristics of approximately400 chemicals, representing various classes of energetic materials, were summarized by chemical class and statistically analyzed. Average decomposition characteristics, such as energy of decomposition and decomposition onset temperature, were determined for chemical classes containing the following energetic groups: nitro, nitroso, N-oxide, oxime, hydroxylamine, tetrazole, azide, triazene, triazole, diazo, azo, hydrazine, and perchlorate. Additional statistical information is presented for each chemical class, such as number of chemicals analyzed, ranges, and standard deviations for the decomposition parameters analyzed. For chemical classes containing an energetic group attached to an aromatic ring, the presence and position of another substituting group in the ring can significantly influence the decomposition onset temperature. The study summarizes the list of activating and deactivating functional groups, and the positions in the ring where the strongest activation or deactivation occurs. The authors also recommend a method for estimating decomposition parameters of new chemicals.

Multifunctional Linkers as an Efficient Tool for the Synthesis of Diverse Small Molecule Libraries: The Triazene Anchors

Abstract: Publisher Summary Triazenes provide new possibilities for the activation of the ortho-position of arenes by coordination of metal ions and/or by lowering the electron density of the arene ring, they are also ideal synthons for diazonium salts. This chapter discusses two linkers based on the triazene chemistry, T 1 and T 2, used for the synthesis of diverse small molecule libraries. While the T 1 linker system consists of 3,3-dialkyl-1 aryl triazene bound to the support via the alkyl chain, the T 2 linker family is based on immobilized aryl diazonium salts. The triazene T 1 linker has been successfully used as a linker for arenes. While the T 1 linker involves an immobilization of a diazonium salt on an amine resin, the T 2 linker represents the reversal of this concept. The T2 linker has recently been shown to be a versatile backbone amide anchor. Immobilized disubstituted triazenes were acylated with carboxylic acid anhydrides or chlorides to give amide derivatives. These amides were cleaved under very mild conditions using trimethyl chlorosilane. This sequence thus, employs the T 2 system as backbone amine linker and was demonstrated in the automated library synthesis of substituted amide derivatives.

1,3-Bis(4-nitrophenyl)triazene.

Abstract: The structure of the title compound, C(12)H(9)N(5)O(4), reveals an almost planar molecule (r.m.s. deviation = 0.061 A), in which the interplanar angle between the phenyl rings is 5.7 (1) degrees and the largest interplanar angle is that between the phenyl ring and the nitro group of one of the 4-nitrophenyl substituents [8.8 (3) degrees ]. The observed molecular conformation suggests a delocalization of pi-electrons extended over the diazoamine group and the terminal aryl substituents. Intermolecular N-H.O interactions between the twofold screw-related molecules give rise to helical chains along the [010] direction. Intermolecular C-H.O interactions then generate sheets of molecules in the (10-1) plane, and these sheets are held together by N.C and O.O pi-pi interactions.

Efficient synthesis of sulfonic, phosphoric, and phosphinic esters employing alkylating polymer-bound reagents.

Abstract: The efficient esterification of various sulfonic acids and sulfonates using polymer-bound triazenes based on the triazene T2* linker is described. Esterification of enantiopure α-substituted sodium...

Synthesis of 1-[4-(m-tolyl)amino-6-quinazolinyl]-3-[14C]-methyl triazene: a radiolabeled probe for the combi-targeting concept

Abstract: The synthesis of 1-[4-(m-tolyl)amino-6-quinazolinyl]-3-[14C]-methyl triazene (SMA41) is described. This triazene was designed to be hydrolyzed under physiological conditions to N4-m-tolyl-quinazoline-4,6-diamine (SMA52), a moderate inhibitor of the epidermal growth factor receptor (EGFR) and the DNA alkylating species [14C]-methyldiazonium. A radiolabeled probe was needed to test the hypothesis that in situ hydrolysis of SMA41 may induce alkylation of the ATP binding site of EGFR. 14C-SMA41 was obtained with a radiochemical yield of 21% and a specific activity of 54.6 mCi/mmol, as determined by HPLC quantitation and scintillation counting. Radio-TLC analyses showed 98% radiochemical purity. Copyright © 2003 John Wiley & Sons, Ltd.

Synthesis and Structure of K[Cd(O2N‐C6H4‐NNN‐C6H4‐NO2)3], an Anionic 1, 3‐Bis(4‐nitrophenyl)triazenido Complex of Cadmium

Abstract: The reaction of cadmium acetate in methanol with 1, 3-bis(4-nitrophenyl)triazene in THF in the presence of KOH yields K[Cd(O2NC6H4NNNC6H4NO2)3] in form of hexagonal prismatic, red crystals with the trigonal space group R3¯ and a = 12.229(2), c = 48.988(10) A and Z = 6. In the anionic cadmium complexes, which are located along the threefold axis, the Cd atoms are coordinated in a trigonal prismatic arrangement by the atoms N(1) and N(3) of three triazenido ligands. The potassium cations are coordinated icosahedrally by oxygen atoms of each one nitro group of six neighbouring anionic complexes. The Cd-N distances are 2.376(4) and 2.350(4) A, and the K-O distances are in the range of 2.833(6) to 3.365(6) A.

Laser induced decomposition of a designed and a commercial polymer studied by ns-interferometry and shadowgraphy

Abstract: Commercially available polymers often exhibit quite poor laser ablation properties for irradiation wavelengths around 248 nm At these wavelengths, the absorption is due to photostable aromatic groups Photolabile triazene polymers were developed to compare the influence of a photolabile group on the laser ablation process The photochemically active triazene group has a strong absorption band at 332 nm, whereas the second absorption maximum at 220 nm is due to the photostable aromatic group By irradiating at 308 nm and 193 nm, the influence of the photochemically active group on the ablation process can be studied The etching of the triazene polymer starts and ends with the laser pulse No surface swelling, which is assigned to photothermal ablation, is detected for fluences above the threshold of ablation The expansion of the laser ablation induced shockwave was measured for the photolabile triazene polymer and the photostable polyimide The speed of the shockwave increases with fluence and is higher for irradiation with 193 nm than with 308 nm A shockwave with equal or higher velocity is observed for the triazene polymer compared with polyimide

Cyclization of 1-(2-Alkynylphenyl)-3,3-dialkyltriazenes: A Convenient, High-Yield Synthesis of Substituted Cinnolines and Isoindazoles.

Abstract: A new route to isoindazoles and cinnolines through the cyclization of (2-alkynylphenyl)triazenes under neutral conditions is presented. The products that result from heating the starting triazenes depend on both the type of alkyne ortho to the triazene functionality and the temperature used. Butadiyne moieties ortho to dialkyltriazenes yield bis-isoindazole dimers when heated to 150 °C in MeI. A requirement for cyclization in MeI is that the (2-alkynylphenyl)triazene must contain a suitably electron-withdrawing substituent on the phenyl ring to deactivate the triazene toward methylation-induced decomposition to an iodoarene. Ethynyl moieties ortho to dialkyltriazenes yield both isoindazole dimers as well as 3-formylisoindazoles when subjected to the same conditions. Replacing MeI with 1,2-dichlorobenzene as solvent allows for the general cyclization of (2-ethynylphenyl)dialkyltriazenes. Heating to 170 °C results in a mixture of isoindazole and cinnoline products, whereas the cinnolines are produced exclus...

Current advances of triazene reagents in photometric analysis

Abstract: A review on the application of triazene reagents in photometric analysis during the period of 1995 to 2001 is given with 61 references,including structures of reagent,characters of chromogenic reaction,reaction mechanism and some applications.

A New Synthesis of Temozolomide.

Abstract: An efficient condensation reaction between nitrosoimidazoles and phenyl methylcarbazate forms the basis of a new synthetic route to phenyloxycarbonyl substituted triazenylimidazoles. Exposure of these triazenes to diffuse daylight is sufficient to induce (E) to (Z)-isomerization of the triazene –NN– bond, resulting in spontaneous formation of temozolomide in high yield.