Search results for " Active"
showing 10 items of 533 documents
Studien zum Vorgang der Wasserstoffübertragung, 57 Einige Beispiele zur diastereoselektiven Hydrierung von Verbindungen mit prochiralen CC-Bindungen
1979
(1R,2S)-N,N-Dimethylephedriniumchlorid, (1S,2S)-N,N-Dimethylpseudoephedriniumchlorid, (1R,2S)-N-Methylephedrin, (1S,2S)-N-Methylpseudoephedrin und [(2S)-2-Hydroxy-2-phenyl-ethyl]trimethylammoniumchlorid werden mit α- und β-Methylzimtsaure zu 1–4 und 7 verestert und an Raney-Nickel, Palladium, Platin und einer Reihe von Edelmetalltragerkatalysatoren hydriert. Die hydrierten Ester werden verseift und die optische Ausbeute der α- bzw. β-Methyldihydrozimtsaure bestimmt. Die optischen Ausbeuten bewegen sich in Abhangigkeit von der optisch aktiven Hilfskomponente zwischen 68 und 4%. Bei optischen Ausbeuten uber 10% wird die absolute Konfiguration der α- oder β-Methyldihydrozimtsaure von der Konfi…
PHOSPHORORGANISCHE VERBINDUNGEN 931
1980
Abstract Optisch aktives Ethyl-phenyl-phosphinigsaurediethylamid 1 wird in racemische literaturbekannte Verbindungen uber-gefuhrt bei der Einwirkung von HCl, HBF4, Alkoholen, Thioalkoholen, Carbonsauren, Carbonsaureestern, Carbonsaureanhydriden, Carbonsaurehalogeniden, Verbindungen mit Pl und sekundaren Phosphinen. p-Kresol, Trifluoressigsaure-p-kresylester sowie Trifluoressigsaure-s,s,s-trifluorethylester setzen sich mit optisch aktivem Ethyl-phenyl-phosphinigsaure-diethylamid 1 unter Erhaltung der Konfiguration zu den entsprechenden optisch aktiven Ethyl-phenyl-phosphingsaureestern um. Optically active ethyl-phenyl-phosphinous acid diethylamide 1 was treated with HCl, HBF4, alcohols, thio…
Enantioselective Synthesis of Unsymmetrical Benzoins from (S)-Mandelic Acid Enolate and Aromatic Aldehydes.
2004
The reaction of the lithium enolate of the 1,3-dioxolan-4-one derived from optically active (S)-mandelic acid and pivalaldehyde with aromatic aldehydes proceeds readily to give the corresponding aldol products in good yields and diastereoselectivities. Subsequent hydroxyl protection, basic hydrolysis of the dioxolanone, oxidative decarboxylation of the α-hydroxyacid moiety, and hydroxyl deprotection provides chiral unsymmetrical benzoins with high enantiomeric excesses.
Advances in the understanding of mast cell function
2008
Mast cells were formerly thought to contribute mainly to, sometimes even, fatal allergic reactions through the release of biologically highly active cytokines, chemokines, lipid mediators, proteases and biogenic amines. This potential harmful response is triggered by crosslinking of cell-bound IgE by the respective allergen. This review updates our current understanding of the emerging roles of mast cells with an emphasis on their relevance in protective host immunity. The activation of mast cells independently of Immunoglobulin E can lead to the initiation of fast inflammatory reactions, which were shown to be life-saving in murine models of bacterial infections. Besides their critical fun…
A lymphocyte-glia connection sets the pace for smoldering inflammation
2021
Successful therapeutic options directly targeting disability progression in patients with multiple sclerosis (MS), a chronic inflammatory disorder of the central nervous system, are lacking. Now, a study published in Nature by Absinta and colleagues profiles a lymphocyte-glia connection at the edge of chronic active lesions that continuously drives neurodegenerative pathways.
Ein optisch aktives Polyamid mit atropisomeren Binaphthyl-Grundbausteinen
1968
Zur Darstellung eines optisch aktiven Polyamids mit atropisomeren Grundbausteinen in der Hauptkette wurde (+)-2.2′-Diamino-binaphthyl-(1.1′) (II) hergestellt. Die Drehwerte in einigen Losungsmitteln sowie optische Rotationsdispersion (ORD), Circulardichroismus (CD) und UV-Spektrum werden angegeben. Durch Grenzflachenpolykondensation von II mit Terephthaloylchlorid wurde ein optisch aktives Polyamid (III) erhalten. Drehwerte, ORD und CD von III werden gemessen und mit denen des als Modellsubstanz dargestellten (+)-2.2′-Dibenzamido-binaphthyls-(1.1′) (IV) verglichen. Beide Substanzen zeigen mehrere COTTON-Effekte, die hinsichtlich ihres Vorzeichens ubereinstimmen. In ihrer Lage sind jedoch di…
Multistate active spaces from local CAS-SCF molecular orbitals: the photodissociation of HFCO as an example.
2005
A recently developed algorithm to generate localized molecular orbitals (LMO) is applied to the study of excited states along a photodissociation process. The LMOs allow for the selection of a consistent complete active space (CAS) for the simultaneous description of all the electronic states involved in a multistate process on the basis of simple chemical criteria. The local nature of the orbitals is used to label them in a unique way that does not depend on the molecular geometry. The selection of the electronic configurations of interest for the set of target states on only the basis of the dominant excitations required by the simplest configuration interaction (CI) descriptions for both…
Vertical spectrum of the C2H 2+ system. An open shell (SC)2-CAS-SDCI study
2003
The open shell (SC)(2)-CAS-SDCI method along with a basis set of atomic natural orbitals (ANO) has been applied for calculating the main ionization potentials of acetylene, as well as the manifold of excited states of the different symmetries up to 32 eV. In this method, the single and double excitations of a CAS space are generated and the corresponding CI matrix is corrected by means of the (SC)(2) procedure that cancels the size-extensivity error and adds some high order contributions. The mean absolute error for the outer-valence X (2)Pi(u)(1pi(u) (-1)), A (2)Sigma(g) (+)(3sigma(g) (-1)), and B (2)Sigma(u) (+)(2sigma(u) (-1)) states, and the inner-valence C (2)Sigma(g) (+)(2sigma(g) (-1…
State-specific multireference coupled-cluster theory
2012
The multireference problem is considered one of the great challenges in coupled-cluster (CC) theory. Most recent developments are based on state-specific approaches, which focus on a single state and avoid some of the numerical problems of more general approaches. We review various state-of-the-art methods, including Mukherjee's state-specific multireference coupled-cluster (Mk-MRCC) theory, multireference Brillouin–Wigner coupled-cluster (MR-BWCC) theory, the MRexpT method, and internally contracted multireference coupled-cluster (ic-MRCC) theory. Related methods such as extended single-reference schemes [e.g., the complete active space coupled-cluster (CASCC) theory] and canonical transfo…
A New Platform for Automatic Bottom-Up Electric Load Aggregation
2017
In this paper, a new virtual framework for load aggregation in the context of the liberalized energy market is proposed. Since aggregation is managed automatically through a dedicated platform, the purchase of energy can be carried out without intermediation as it happens in peer-to-peer energy transaction models. Differently from what was done before, in this new framework, individual customers can join a load aggregation program through the proposed aggregation platform. Through the platform, their features are evaluated and they are clustered according to their reliability and to the width of range of regulation allowed. The simulations show the deployment of an effective clustering and …