Tuning the photophysical properties of BODIPY molecules by π-conjugation with Fischer carbene complexes.

The synthesis, structure, and photophysical properties of novel BODIPY-Fischer alkoxy-, thio-, and aminocarbene dyads are reported. The BODIPY chromophore is directly attached to the carbene ligand by an ethylenic spacer, thus forming donor-bridge-acceptor π-extended systems. The extension of the π-conjugation is decisive in the equilibrium geometries of the dyads and is clearly reflected in the corresponding absorption and emission spectra.

Regio- and diastereoselective stepwise [8 + 3]-Cycloaddition reaction between tropone derivatives and donor-acceptor cyclopropanes.

A novel SnCl4-catalyzed [8 + 3]-cycloaddition reaction between tropone derivatives and donor-acceptor aminocyclopropanes is described. The process leads to the formation of amino-substituted tetrahydrocyclohepta[b]pyrans with complete regio- and diastereoselectivity. Density functional theory calculations suggest that the cycloaddition occurs stepwise through an aromatic zwitterionic intermediate.

Platinum-catalysed bisindolylation of allenes: a complementary alternative to gold catalysis.

Pt versus Au: Platinum-catalysed addition of nucleophiles to allenes follows a distinctly different pathway to the process catalysed by gold(I) complexes; the platinum catalyst leads to different products with indoles involving a bisindolylation reaction, whereas gold(I) gives allyl indoles from a single addition (see scheme).

Facile deferration of commercial fertilizers containing iron chelates for their NMR analysis.

Ethylenediamine-N,N'-bis(o-hydroxyphenylacetic) acid (o,o-EDDHA) is widely used in commercial formulations as a Fe(3+) chelating agent to remedy iron shortage in calcareous and alkaline soils. Commercially available o,o-EDDHA-Fe(3+) formulations contain a mixture of EDDHA regioisomers (o,p-EDDHA and p,p-EDDHA), together with other, still uncharacterized, products. NMR spectroscopy can be applied to their study as long as iron is accurately removed prior to the observation.