The efficiency of a chemical synthesis can be nowadays measured, not only by parameters like selectivity and overall yield, but also by its raw material, time, human resources and energy requirements, as well as the toxicity and hazard of the chemicals and the protocols involved. The development of multicomponent reactions (MCRs) in the presence of task-specific ionic liquids (ILs), used not only as environmentally benign reaction media, but also as catalysts, is a new approach that meet with the requirements of sustainable chemistry. The aim of this tutorial review is to highlight the synergistic effect of the combined use of MCRs and ILs for the development of new eco-compatible methodologies for heterocyclic chemistry.

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Thirteen crystal structures document the general phenomenon of coordination-hole contraction in hexahydro-and tetrahydroporphinoid ligands of complexes with small metal ions such as low-spin Ni(I1). The contraction is characterized by a deformation of the ligand system towards a saddle-shaped, ruMed conformation of approximate S, symmetry. The central metal ion is coplanar with the four coordinating N-centers whereas the four C(meso)-atoms arc situated alternately above and below this coordination plane. Increasing steepness of the saddle (parameter d,) is associated with decreasing metal-N distances. For metal pyrrocorphinates, d, increases in the order Cu(11) < (pyridine) Co(l1) < Ni(II), for Ni(1l) complexes it does so in the order porphyrin < chlorin ' ) ')Beziehbar von der Hauptbibliothek der ETH Zurich. Alle in dieser Arbeit vorkommenden chiralen Verbindungen waren in racemischer Form.

The first enantiopure N-fluoro quaternary ammonium salts of cinchona alkaloids as enantioselective fluorinating agents are reported. A one-step transfer-fluorination on the naturally occurring cinchona alkaloids gave the fluorinating agents F-CA-BF(4). This new generation of fluorinating agents exhibited asymmetric induction up to 61% on fluorination of enolates and silyl enol ethers of 2-methyl-1-tetralone.

Both isothermal attrition-enhanced and ultrasoundenhanced deracemizations of an organic compound were compared in productivities and in the evolution of the crystal size distributions. These shed new light on the underlying mechanisms, drawing attention to the existence of several agonist effects and particularly the role of entrainment in the deracemization process.

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