Mitt. XV: Struktur und reaktivität von isoanellierten heterocyclischen systemen mit 4nπ- und (4n + 2) π-elektronen. 2-t-butyl-4-methyl-2,4-dihydropyrrolo[3,4-b]indole. reaktionen mit aktivierten CC-dienophilen

Reactions of 2-t-butyl-4-methyl-2,4-dihydropyrrolo[3,4-b]indoles with N-aryl-maleimides have been investigated. The formation of 1:1-cycloadducts is influenced by substituents at 1,3-position. The consecutive transformations of these intermediates can be controlled by nucleophilic solvents or reagents. Ring opening reactions occur at the labile N,O-acetal group of the cycloadducts followed by eliminaton or addition reactions.     

Azadepsipeptides: synthesis and evaluation of a novel class of peptidomimetics

A general route to azadepsipeptides, a new class of pseudopeptides, has been established. The methodology was applied to the synthesis of a bis-aza analogue of the antiparasitic cyclooctadepsipeptide PF1022A. Comparison of the X-ray crystal structures of natural PF1022A (8) and the chimeric aza analogue 9 revealed that the introduction of nitrogen in the backbone of PF1022A results in almost complete conservation of the 3D structure with only minor deviations at the new nitrogen positions.     

Tetrapyridoxycalix[4]arene and its copper(II) complex: an ionic crystal engineering tecton for self-inclusion polymers

The crystal structures of a tetradentate pyridylcalix[4]arene ligand and its first copper(II) complex are discussed. The metal free ligand is mainly self-assembled by dipole–dipole interactions and a combination of CH–N bonds and CH–π interactions. The corresponding copper(II) perchlorate complex exhibits a self-inclusion behaviour to supramolecular zig-zag polymers.