Search results for "stereo"
showing 10 items of 6147 documents
Pyrido[2’,3’:4,5]pyrrolo[2,1-d][1,2,3,5]tetrazine-4(3H)-ones, a new class of temozolomide heteroanalogues
2009
Twelve derivatives of new ring system pyrido[2’,3’:4,5]pyrrolo[2,1-d][1,2,3,5]tetrazine were prepared in good yields by reaction of 2-diazo-3-ethoxycarbonyl-pyrrolo[3,2-b]pyridine with alkyl- or aryl-isocyanates. Nine derivatives, screened by the National Cancer Institute (Bethesda, MD) for the in vitro one dose primary anticancer assay against a panel of about 60 human tumor cell lines, showed no significant activity.
Diastereoselective synthesis of 6-functionalized 4-aryl-1,3-oxazinan-2-ones and their application in the synthesis of 3-aryl-1,3-aminoalcohols and 6-…
2010
Abstract Halocyclocarbamation of benzyl N -(1-phenyl-3-butenyl)carbamates afforded 6-functionalized 4-aryl-1,3-oxazinan-2-ones with moderate to excellent diastereoselectivity depending on the N -substituent. Importantly, in contrast to reported cyclocarbamations of homoallylic carbamates, which are generally trans -diastereoselective, cyclization of N -unsubstituted Cbz-protected homoallylamines led to cis -1,3-oxazinan-2-ones, predominantly. The use of N -benzylated and in situ prepared N -silylated derivatives resulted however in trans -selectivity. Transition states are proposed to explain the stereochemical influence of the N -substituent on the cyclocarbamations. The functionalized 1,3…
Enhanced field-of-view integral imaging display using multi-Köhler illumination.
2014
A common drawback in 3D integral imaging displays is the appearance of pseudoimages beyond the viewing angle. These pseudoimages appear when the light rays coming from each elemental image are not passing through the corresponding microlens, and a set of barriers must be used to avoid this flipping effect. We present a pure optical arrangement based on Köhler illumination to generate these barriers thus avoiding the pseudoimages. The proposed system does not use additional lenses to project the elemental images, so no optical aberrations are introduced. As an added benefit, Köhler illumination provides a higher contrast 3D display. This work was supported in part by the Plan Nacional I + D …
Synthesis of New 2-{[(Phenoxy or Phenyl)acetyl]amino}benzoic Acid Derivatives as 3α-Hydroxysteroid Dehydrogenase Inhibitors and Potential Antiinflamm…
1995
A number of 2-([(phenoxy or phenyl)acetyl]amino)benzoic acid derivatives were prepared in about 50% yield from (phenoxy or phenyl)acetyl chloride and anthranilic acid derivatives. All the compounds were tested as in vitro inhibitors of 3 alpha-hydroxysteroid dehydrogenase, since enzyme inhibition predicts potential antiinflammatory activity in vivo. The most active compounds 3 l, m, s are about 3.5 times more active than acetylsalicylic acid (ASA). Activity is influenced by electronic as well as steric effects.
“Twin” phosphorous atoms of tetraethyl 2-methyl-piperyd-1-ylmethylenebisphosphonates
2007
Recently, bisaminophosphonates found applications as therapeutic agents for curing bone disorders. When trying to relate the structures of substituted piperid-1-ylmethylenebisphosphonic with their biological properties, non-typical findings that in 31P NMR spectra of 2-methyl-piperid-1-ylmethylenebisphosphonic and 2-ethyl-piperid-1-ylmethylenebisphosphonic acids, two separate singlets from each of the phosphonic groups were observed, while their analogues bearing substituent in position 3 exhibit only one signal. Their presence was explained by freezing of the molecular motions by strong hydrogen bonding between NH and P = O atoms. In this work, synthesis as well as spectroscopic and theore…
The emerging role of 3D printing in the fabrication of detection systems
2021
Abstract 3D printing is fast evolving as an additive manufacturing technique that has been adopted in (bio)analytical science because of the ample variety of materials and technologies currently available for highly affordable prototyping. This review focuses on the unique characteristics of 3D printing for manufacturing of optical and electrochemical detection systems, and sampling interfaces for analytical purposes using fused deposition modelling, vat polymerization (stereolithography and digital light processing) and photopolymer inkjet printing. The majority of works surveyed within the time span of mid-2018 to mid-2020 encompassed the fabrication of several components of the detection…
Synthesis of (+) and (‐)‐Streptomyces coelicolor Butanolide 5 (SCB‐5)
2021
Exploration of the Activation Mechanism of the Epigenetic Regulator MLL3: A QM/MM Study
2021
The mixed lineage leukemia 3 or MLL3 is the enzyme in charge of the writing of an epigenetic mark through the methylation of lysine 4 from the N-terminal domain of histone 3 and its deregulation has been related to several cancer lines. An interesting feature of this enzyme comes from its regulation mechanism, which involves its binding to an activating dimer before it can be catalytically functional. Once the trimer is formed, the reaction mechanism proceeds through the deprotonation of the lysine followed by the methyl-transfer reaction. Here we present a detailed exploration of the activation mechanism through a QM/MM approach focusing on both steps of the reaction, aiming to provide new…
Voice and identity: a contrastive study of identity perception in voice
2009
En mi tesis doctoral he estudiado qué elementos suprasegmentales de la voz se combinan a nivel prosódico para transmitir información sobre nuestra identidad (origen, personalidad, emociones.). En la parte teórica se define el concepto de identidad, llegando a la conclusión de que identidad es un término relacional que construye un paralelismo entre dos campos, el de la individualidad y el de la colectividad. En el marco teórico se tratan distintas teorías como el constructivismo radical y el experiencialismo radical para comprender cómo la percepción, la estereotipación y la categorización de la voz son actores indispensables a la hora de utilizar la voz o escuchar otras voces. En la parte …