Search results for "44"

Triazolopyridines 22.1 Description of new 7,9-di(2-pyridyl)[1,2,3]triazolo[5',1':6,1]pyrido[3,2-d]pyrimidines

2002

The new heteroaromatic compounds, 7,9-di(2-pyridyl)(1,2,3)triazolo(5',1':6,1)pyrido(3,2-d) pyrimidines 11a-c, were synthesized in two steps from readily available triazolopyridines 1a-c. Regioselective lithiation of 1a-c followed by treatment with 2-cyanopyridine gave a mixture of compounds 5a-c, and 11a-c in moderate to low yields, together with gums. Similar reactions with the triazolopyridine 1d gave as the only identified compound the triazolopyridine derivative 5d.

SYNTHESIS AND PHARMACOLOGICAL EVALUATION OF 7-SUBSTITUTED1-ETHYL-3,4,10-TRIMETHYL-1,10-DIHYDRO-11H-PYRAZOLO(3,4-c)(1,6)BENZODIAZOCIN-11-ONE: A NEW RI…

2004

Derivatives of the title ring system of type 10 were obtained in good yield by fusion of the intermediates 12. Attempt to cyclize the acetylamino derivative 9 under Bischler-Napieralski conditions failed because of the insufficient electronic density in the position 4 of the pyrazole ring created by the adjacent carbonyl moiety. The derivatives of the new ring system, assayed as anxiolytic agents, showed no significant activity.

Synthesis of pyrazole-4-carbohydrazide derivatives of pharmaceutical interest

2003

New 1-phenylor 1-methyl-5-benzamidopyrazole-4-carbohydrazide derivatives were prepared in 70–90% yields from 1-methylor 1-phenyl-6-phenylpyrazolo[3,4-d]1,3-oxazin-4(1H)-one derivatives and hydrazine hydrate. Small quantities of the isomeric 5-aminopyrazole-4-(Nbenzoyl)hydrazides were detected in some reaction mixtures, proving that intramolecular benzoyl migration can take place in the 5-benzamidopyrazole-4-carbohydrazide molecule. The direct formation of pyrazole-4-carbohydrazides from 5-benzamidopyrazole-4-carboxylic acid ethyl esters and hydrazine hydrate was unsuccessful.

Synthetic approaches towards huperzine A and B

2013

Huperzine A and B are potent acetylcholinesterase inhibitors and promising against Alzheimer's disease. Completed and formal total syntheses of these medically relevant alkaloids are presented and discussed.

Kinetics of photochemical isomerization of TFA-Gly-ZΔPhe into TFA-Gly-EΔPhe

2017

The kinetics of photoisomerization of trifluoroacetyl-(Z)-dehydrophenylalanylglycine into trifluoroacetyl-(E)- dehydrophenylalanylglycine was studied in the hope that light-induced reaction could be useful as a means of preparation of the E-dehydropeptides. The obtained results indicate that if this reaction carried out under irradiation with light of wavelength 360 nm it is practically irreversible and gave nearly quantitatively pure Eisomer Significantly, expected cyclic side-products were not observed in the reaction mixture, thus proving the preparative potential of the elaborated procedure.

Synthesis of 6,12-Disubstituted Methanodibenzo[b,f][1,5]dioxocins : Pyrrolidine Catalyzed Self-Condensation of 2′-Hydroxyacetophenones

2019

The preparation of unprecedented 6,12-disubstituted methanodibenzo[b,f][1,5]dioxocins from pyrrolidine catalyzed self-condensation of 2′-hydroxyacetophenones is herein described. This method provides easy access to this highly bridged complex core, resulting in construction of two C–O and two C–C bonds, a methylene bridge and two quaternary centers in a single step. The intricate methanodibenzo[b,f][1,5]dioxocin compounds were obtained in up to moderate yields after optimization of the reaction conditions concerning solvent, reaction times and the use of additives. Several halide substituted methanodibenzo[b,f][1,5]dioxocins could be prepared from correspondent 2′-hydroxyacetophenones.

Photochemistry of triazolopyridinium ylides

2000

Glycosidopyrroles. Part 4. 1-β-D-ribofuranosyl-pyrroles and indoles as potential antiviral agents

2000

The preparation of new 1-β-D-ribofuranosylpyrroles of type 8 and a new method of synthesis of 1-β-D-ribofuranosylindoles of type 10, according to the scheme, is reported. All these new derivatives showed promising chemical and physical analogies with bioactive molecules but did not show any antiviral activity againstHIV1.

Triazolopyridines 21.1 The stereochemistry of 1-[1,2,3]triazolo[1,5-a] pyridin-7-yl-4-(2H-[1,2,3]triazol-4-yl)-1,3-butadienes and triazolo ring openi…

2002

The synthesis and NMR study of the geometry of 1-[1,2,3]triazolo[1,5-a]pyridin-7-yl-4-(2H[1,2,3]triazol-4-yl)-1,3-butadienes 1a, 1b, 5 and of new 1-(6-substituted-2-pyridyl)-4-(2H[1,2,3]triazol-4-yl)-1,3-butadienes 8-10 is reported. The stereochemistry of all butadienes studied is 1E, 3E except for compound 5 that is the 1Z, 3Z stereoisomer of 1a.

Flow Behavior of Chain and Star Polymers and Their Mixtures

2018

Star-shaped polymers show a continuous change of properties from flexible linear chains to soft colloids, as the number of arms is increased. To investigate the effect of macromolecular architecture on the flow properties, we employ computer simulations of single chain and star polymers as well as of their mixtures under Poiseuille flow. Hydrodynamic interactions are incorporated through the multi-particle collision dynamics (MPCD) technique, while a bead-spring model is used to describe the polymers. For the ultradilute systems at rest, the polymers are distributed uniformly in the slit channel, with a weak dependence on their number of arms. Once flow is applied, however, we find that the…