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Semiempirical and ab initio quantum chemical computations indicate that the intermediate formed prior to the selectivity-determining methyl transfer step in the reaction between glycosides and trimethylaluminum is a strongly hydrogen-bended equilibrium OH...C = O-H...C, which is proposed to be an important selectivity promoting factor in the alkyl transfer reaction.
The primary aim of this thesis is to develop a theoretical model that enhances our understanding of entrepreneurial learning as a process by which personalized streams of experience become routinized and embedded in venture-wide behaviors. The aim is realized by exploring entrepreneurial learning as an experiential multilevel process. This process begins with learning at the individual level, whic
Simple lactol ethers undergo ring cleavage to give acyclic chain-extended products on treatment with organoaluminium and organotitanium reagents.
Combinations of Lewis acids and nucleophilic reagents trigger endo-opening of the furanoside ring of methyl furanosides 1, 10 and 13, resulting in the attachment of the nucleophilic group at C-1 of the carbohydrate. The stereoselectivity in the C-C bond-forming step is low for the 2-deoxyfuranosides but very high (dr 1:99) for the furanosides carrying a methoxy group in the 2-position when a combi
A number of pentopyranoside derivatives were treated with Me 3 Al in order to investigate the influence of structural parameters on the methyl group transfer in the endocyclic alkylative cleavage reaction of these substrates. A cyclic CH ··· O hydrogen bonded model is suggested as an intermediate, which is used to explain the stereoselectivities for different substrates. In several, cases the dia
The results presented are the first examples where organotitanium reagents induced alkylative endo-cleavage of carbohydrates. The best conditions for the alkylative transfer of a methyl group to benzyl 2-deoxy- 2-C-methyl-4-O-(tert-butyldimethylsilyl)-α-D-arabinopyranoside (1) were the application of one equivalent of AlMe3 followed by four equivalents of MeTiCl3 generated by mixing TiCl4 and ZnMe
An efficient enantiospecific synthesis of D-erythro-sphingosine (1) via azidosphingosine (2) is described, the absolute stereochemistry being derived from D-tartaric acid.
Current antipsychotic drug therapies for schizophrenia have limited efficacy and are notably ineffective at addressing the cognitive deficits associated with this disorder. The present study was designed to develop effective antipsychotic agents that would also ameliorate the cognitive deficits associated with this disease. In vitro studies comprised of binding and functional assays were utilized
Figure presented Sequential addition of Grignard reagents to pyridine N-oxides in THF at room temperature followed by treatment with acetic anhydride at 120°C afforded 2-substituted pyridines in good to high yields. Furthermore, by exchanging acetic anhydride for DMF in the second step, 2-substituted pyridine N-oxides were obtained, as intermediates suitable for addition of a second Grignard reage
The binding pocket of both NPFF receptors was investigated, focusing on subtype-selective behavior. By use of four nonpeptidic compounds and the peptide mimetics RF9 and BIBP3226, agonistic and antagonistic properties were characterized. A set of Ala receptor mutants was generated. The binding pocket was narrowed down to the upper part of transmembrane helices V, VI, VII and the extracellular loop
The removal and degradation of refractory antibiotics in saline water by electrochemical and photo-electrochemical catalysis has emerged as a worldwide research hotspot. Aiming to improve degradation performance, most of the concerned studies focus on new sophisticated materials and modification methods on the single working electrode (anode or cathode). But the synergistic effects between anode a
