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At least 1,045 records · Page 58Linked to original sources
PubMed2004

Pyrazolo[3,4-d][1,2,3]triazine DNA: synthesis and base pairing of 7-deaza-2,8-diaza-2'-deoxyadenosine.

7-deaza-2,8-diaza-2'-deoxyadenosine (4) was synthesized from 8-aza-7-deaza-2'-deoxyadenosine (1) via the 1,N(6)-etheno derivative 5. Ring opening with sodium hydroxide followed by ring closure in the presence of sodium nitrite formed the tricyclic intermediate 5 from which the transiently introduced "etheno" moiety was removed with NBS. Compound 4 was converted to the phosphoramidite 11, which was employed in solid-phase oligonucleotide synthesis. Base pairing studies on 4, incorporated in a 12-mer duplex, showed that this adenine nucleoside analogue forms a strong base pair with dG but not with dT. This novel base pair is as stable as that of the canonical dA-dT pair. As a result of the absence of nitrogen-7 compound 4 is expected to form a face to face base pair with dG.

Base Pairing↗
PubMed2005

A novel method for the synthesis of imidazo[5,1-f][1,2,4]triazin-4(3H)-ones.

[reaction: see text] Imidazo[5,1-f][1,2,4]triazinones, as isosteres of purine, are of interest for pharmaceutical research. The syntheses reported in the literature generally require several steps. We report a novel method to access a broad range of diversely substituted derivatives. The key step is the electrophilic N-amination of 3H-imidazoles containing a 4-carbonyl group. Several different substituted imidazoles have been N-aminated in this manner. The resulting N-aminoimidazoles were cyclized under different conditions to the corresponding imidazotriazinones, which allowed for additional diversification. This novel method was applied in a formal synthesis of vardenafil, a well-known representative of this class of compounds. Furthermore, we report the first synthesis of a 7-aryl-imidazotriazinone via bromination of an unsubstituted imidazotriazinone followed by a Suzuki coupling.

Imidazoles↗
PubMed2005

The ultrafast dynamics and nonlinear optical properties of tribranched styryl derivatives based on 1,3,5-triazine.

By using the femtosecond laser spectroscopic techniques, we have studied the ultrafast response and the nonlinear optical properties of three molecules with donor-acceptor structure (denoted as T01, T02, and T03). Two-photon absorption (2PA) cross sections measured by the open aperture Z-scan technique were determined to be 77, 90, and 410 GM for T01, T02, and T03, respectively. The relaxation dynamics of the excited states were measured by two-color femtosecond pump-probe and time-resolved photoluminescence (PL) experiments. By changing the solvent from chloroform (CHCl3) to dimethyl sulfoxide (DMSO), the transient dynamics was found changed significantly and the decay time of PL emission decreased dramatically because DMSO with large dipole moment accelerates the cross-transfer process and the nonradiative process in the molecules.

Chemistry, Physical↗
PubMed1986

Low central nervous system penetration of N2,N4,N6,-trihydroxymethyl-N2,N4,N6,-trimethylmelamine (Trimelamol): a cytotoxic s-triazine with reduced neurotoxicity.

Trimelamol (N2,N4,N6-trihydroxymethyl-N2,N4,N6-trimethylmelamine) is an analogue of pentamethylmelamine (PMM). In early clinical trials PMM failed to show significant anti-tumour activity in man which was attributed to poor metabolic activation. Trimelamol does not require activation and is therefore expected to be more active in man. PMM caused dose-limiting emesis and sedation whereas Trimelamol is much less neurotoxic in rodents. The relative penetration of PMM and Trimelamol into mouse brain has therefore been examined. Mice receiving PMM at 90 mg kg-1 i.p. were found to have high concentrations of the drug in the CNS compared to plasma (mean brain/plasma ratio 1.04) whereas animals receiving Trimelamol had consistently low CNS concentrations (mean brain/plasma ratio 0.08). This difference did not correlate with plasma protein binding which is greater for PMM (68.2%) than for Trimelamol (17.5%). However, it does appear to be related to lipophilicity. In Phase I clinical trial Trimelamol has proved much less emetic than PMM and causes no acute sedation. It is likely that this reduction in toxicity may be explained by the relatively poor ability of Trimelamol to enter the CNS.

Altretamine↗
PubMed2004

In vivo study of triazine herbicides in plants by SPME.

The use of SPME for in vivo monitoring of herbicide levels in plant tissues is evaluated. Fibers are exposed to the plant tissue with the aid of buffer located at the fiber/tissue interface region. Following this extraction period the extracted amount is estimated by solvent desorption and LC-MS-MS.

Chromatography, Liquid↗