Search results for "stereo"

From Overstoichiometric to Substoichiometric Enantioselective Protonation with 2-Sulfinyl Alcohols: A View in Perspective

2005

A general study of the enantioselective protonation of prochiral enolates with 2-sulfinyl alcohols is reported. The modification of reaction conditions to reduce drastically the amount of chiral proton source needed to obtain a good enantiomeric excess is reported. The effects of the different factors controlling the stereoselectivity are clearly established. Different protocols for enolate generation are compared.

Synthesis of pyrazolo[4,3-c][1,2,6]benzothiadiazocine, a new ring system as potential COX inhibitor

2012

Derivatives of the new ring system 1,4-dihydropyrazolo[4,3-c][1,2,6] benzothiadiazocin-11(10H)one 5,5-dioxide were synthesized in five or six steps in 57-66% overall yields and tested as COX inhibitors.

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.

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.

New Insights into the complexation of lead(II) by 1,4,7,10-tetrakis(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane (DOTAM): structural, thermodynami…

2007

The lead(II) coordination properties of the tetrapodal ligand DOTAM [1,4,7,10-tetrakis(carbamoylmethyl)-1,4,7,10-tetraaza-cyclododecane] have been investigated both in the solid state and in solution in order to ascertain the stereoactivity of the lone pair and to rationalize the structural effects of a cyclen-based scaffold on the metal uptake kinetics. The crystal structure of the free base shows that the pendant acetamide groups are not equivalent: two are folded over the macrocycle and maintained by an intramolecular hydrogen bond involving an amide hydrogen atom and a neighboring tertiary amine of the cyclen ring, while the other two are extended and point away from the macrocyclic cav…

The Beatles äänistudiossa : Beatles-yhtyeen studiotoiminta historian ja musiikkiteknologian näkökulmasta

1999

Latvijas krievu lietišķā diskursa stereotipisko tekstu organizācijas īpatnības.

2016

Maģistra darbā ir izpētītas Latvijas krievu lietišķā diskursa stereotipisko tekstu īpatnības salīdzinājumā ar latviešu lietišķā diskursa stereotipisko tekstu īpatnībām, kā arī uzskaitītas kopīgās un atšķirīgās iezīmes. Darbs sastāv no divām daļām. Pirmajā – tiek izklāstīti metodiskie paņēmieni, kas nepieciešami lietišķā diskursa un stereotipisko tekstu analīzei. Īpaša uzmanība tiek pievērsta diskursa tipoloģijai, salīdzinošai metodei un diskursa analīzei. Otrā maģistra darba daļa veltīta lietišķās vēstules struktūras analīzei ar tai sekojošu detalizētu lietišķās vēstules komponentu analīzi, galveno uzmanību pievēršot valodas līdzekļu standartizācijai, stereotipiskām konstrukcijām, noturīgām…

Lipase-catalyzed resolution of β-hydroxy selenides

2006

Abstract Eleven β-hydroxy selenides were kinetically resolved using an immobilized lipase (Amano PS-C II) in toluene in the presence of vinyl acetate at 30 °C. This approach provided, in several cases, both enantiomers in high enantiomeric excess. The role of the size of substituents and the behaviour of cyclic β-hydroxy selenides is also discussed. Enantiopure β-hydroxy selenides are useful building blocks. As an application of this chemistry, enantiopure (1 S ,2 R )-indene oxide was obtained in one step from the proper enantiopure β-hydroxy selenide.