Search results for "Miami"

Hirālu piridīna organokatalizatoru izstrāde un pielietojums

2015

Maģistra darba ietvaros tika izstrādāta hirālu DMAP organokatalizatoru sintēze. Iegūto organokatalizatoru aktivitāte tika pārbaudīta tetrazola hemiaminālu dinamiskajā kinētiskajā sadalīšanā.

Integrismo político en EEUU / 3. El peligro hispano

2004

Miami, tourists, colonists and adventurers in the last boundary of Latin America

2012

Preparation of N,O-Aminals as Synthetic Equivalents of H2C=NAr and (H2C=NHAr)+ Ions: Neutral and Acid-promoted Transformations

1988

A general method for the synthesis of N,O-aminals derived from primary aromatic amines is described. The reactivity of these compounds under neutral and acidic conditions has been studied and the title compounds can be envisaged as general purpose H2C=NAr or (H2C=NHAr)+ equivalents. N,O-Aminals have been converted into perhydrotriazines by moderate heating and into bis(4-aminoaryl) methane derivatives or N-benzylarylamines, respectively when heated in acidic media with pH control. Reduction of N, O-acetals with sodium cyanoborohydride has revealed that the C-O bond is broken exclusively in acidic media.

o-Ethoxybenzamid-Mannichbasen als potentielle Prodrugs. o-Ethoxybenzamide Mannich Bases as Potential Prodrugs

1986

An Insight into Substrate-Dependent Fluorination of some Highly Substituted Alicyclic Scaffolds

2017

The substrate-dependent fluorination of some highly-functionalized cyclopentane derivatives with multiple chiral centers has been investigated. The key steps of the stereocontrolled syntheses are the oxidative cleavage of the ring carbon–carbon double bond of readily available diexo or diendo norbornene β-amino acid derivatives followed by transformation of the resulted dialdehyde stereoisomers by reduction. Finally, substrate-directable chemodifferentiation of different types of hydroxy groups under fluorination procedures gave various densely functionalized alicyclic derivatives or heterocycles.

Tetrazola hemiamināls kā hirāla palīggrupa

2017

Tetrazola hemiamināls kā hirāla palīggrupa. Sējējs M., zinātniskais vadītājs Prof., Dr. chem. Sūna E., konsultēja MSc. chem., Kinēns A. Maģistra darbs uzrakstīts latviešu valodā, tā apjoms 58 lapaspuses. Darbs satur 56 attēlus, 5 tabulas. Maģistra darbs veltīts terazolu hemiaminālu hirālās palīggrupas iegūšanai un pielietojumam diastereoselektīvajā sintēzē. Izstrādātās hirālās palīggrupas efektivitāte demonstrēta, ar augstu diastereoselektivitāti veicot karbonskābju α-pozīcijas fluorēšanas un nitrozo-aldola reakcijas. Darba rezultātā izstrādāts tetrazola hemiamināla hirālās palīggrupas stereoindukcijas modelis. Demonstrēta hirālās palīggrupas šķelšana maigos reakcijas apstākļos. Tetrazola h…

A simple and general synthesis of symmetrical and unsymmetrical bis(arylamino)methanes. Reactions of N,O‐acetals with nitrogen bases

1988

Bis(arylamino)methanes 4 free of amine contamination have been efficiently synthesized from N,O-acetals 1 following three different methodologies. The first two are useful for symmetrical aminals and involve the decomposition of an N,O-acetal by a base (phenyllithium or a lithium arylamide) and trapping of the resulting methyleneamine 2 by the equimolar amount of the corresponding arylamine. The third method allows the preparation of either symmetrical or unsymmetrical aminals and consists of decomposing the starting N,O-acetal 1 by heating in vacuo in the presence of the desired arylamine. Ein einfacher und allgemeiner Zugang zu symmetrischen und unsymmetrischen Bis(arylamino)methanen. Rea…

Design, Synthesis, and Biological Evaluation of Novel Fluorinated Ethanolamines

2011

The preparation of novel fluorinated allylamines and their use as key fragments for the stereoselective synthesis of hydroxyethyl secondary amine (HEA)-type peptidomimetics is described. Our strategy employs chiral sulfinyl imines as synthesis intermediates, by treatment of hemiaminal precursors with two equivalents of vinylmagnesium bromide. The subsequent oxidation of the allylic amines to the corresponding epoxides was achieved by treatment with methyl(trifluoromethyl)dioxirane. Finally, epoxide ring opening with a range of nitrogen nucleophiles provided a library of HEA-derived peptidomimetics with a phenyldifluoromethylene moiety. The biological evaluation of these derivatives revealed…

Use of needles and syringes in Miami and Valencia: observations of high and low availability.

2000

Two studies engaged in gathering data on injecting drug users (IDUs) employed supplementary resources to enhance their ethnographic components and compare patterns of use of needles/syringes (n/s) in two geographically similar but culturally distinct cities. Despite its policy of making n/s highly available at fair prices, Valencia, Spain, has markedly higher rates of HIV seroprevalence among its IDUs than does Miami, Florida, where possession of n/s is illegal. Ethnographically based models that track IDUs through choices of injection venues help to explain this difference. Inability of IDUs in Valencia to use their own domiciles as venues for injection contrasts sharply with problems of M…