Migration of copper(II) ions in humic systems-effect of incorporated calcium(II), magnesium(II), and iron(III) ions.

The mobility of heavy metals in natural soil systems can be affected by the properties and compositions of those systems: the content and quality of organic matter as well as the character of inorganic constituents. In this work, the diffusion of copper(II) ions in humic hydrogels with incorporated calcium(II), magnesium(II), and iron(III) ions was investigated. The methods of instantaneous planar source and of constant source were used.

Construction of the Bicyclic Carbon Framework of Euphosalicin.

Our studies toward the total synthesis of the natural product euphosalicin () are presented. Different approaches targeting key intermediates are described, the synthesis of which includes findings on asymmetric dihydroxylations and ring-closing enyne metatheses (RCEYM). Their connection allowed the isolation of highly advanced precursors for studies on macrocyclizations.

Crystal structures of two 1,2,3,4-tetra-hydro-naphthalenes obtained during efforts towards the total synthesis of elisabethin A.

The two substituted 1,2,3,4-tetra-hydro-naphthalenes, methyl ()-3-{(1,4)-6-meth-oxy-4,7-dimethyl-5,8-bis-[(triiso-propyl-sil-yl)-oxy]-1,2,3,4-tetra-hydro-naph-th-al-en-1-yl}butano-ate, CHOSi, (), and methyl ()-3-{(1,4)-8-hy-droxy-6-meth-oxy-4,7-dimethyl-5-[(triiso-propyl-sil-yl)-oxy]-1,2,3,4-tetra-hydro-naphthalen-1-yl}acrylate, CHOSi, (), crystallize in the Sohncke space groups 222 and 2, respectively, with the absolute structure determined on the basis of anomalous dispersion effects. The configurations of the stereo centres in the 1,2,3,4-tetra-hydro-naphthalene moiety of () and () are the same, and the conformation of the non-aromatic part of the ring system is nearly identical. In the crystal of (), weak non-classical C-H⋯O inter-actions consolidate the packing, whereas in (), inter-molecular O-H⋯O hydrogen-bonding inter-actions of medium-to-weak strength direct the mol-ecules into -shaped strands extending parallel to [010].