RESUMO
The divalent iron complexes trans-[FeBr2(BINC)2], [Cp*FeCl(BINC)] (Cp* = Me5C5), and [FeBr2(CNAr3NC)2] with the chelating bis(isonitrile) ligands BINC (bis(2-isocyanophenyl)phenylphosphonate) and CNAr3NC (2,2â³-diisocyano-3,5,3â³,5"tetramethyl-1,1':3',1â³-terphenyl) have been prepared and characterized. Their subsequent reduction yields the di- and trinuclear compounds [Fe3(BINC)6], [Cp*Fe(BINC)]2, [Fe(CNAr3NC)2]2, and [K(Et2O)]2[Fe(CNAr3NC)2]2. The molecular structures of all new species were determined by X-ray crystallography and compared to those of related iron carbonyl complexes, demonstrating that the bidentate isonitrile ligands are capable surrogates for two CO ligands with only minimal distortion of the tetrahedral or octahedral geometry of the parent complexes. The complexes were further characterized by NMR and IR spectroscopy, and the electrochemical properties of selected compounds were analyzed by UV-vis-NIR spectroelectrochemistry.
RESUMO
Isonitriles, being competent σ-donors, show a strong aptitude to form transition-state metal complexes. Nevertheless, until the end of the last century, few metal-isonitrile catalyzed processes were known. Only more recently, scientists recognized the considerable potential of isonitriles as ligands in metal catalysis utilizing both commercially available but also specially designed representatives of this compound class. Isonitrile ligands, which can be both innocent or non-innocent constituents in metal complexes, contributed to the discovery of new catalytic processes and thereby to one of the fastest growing areas of organic chemistry. This review focuses on the special properties and attributes metal-isonitrile complexes offer towards their application in catalysis.
RESUMO
The synthesis of chiral tetrahydrofurans and pyrrolidines starting from 1,2-diols or ß-amino alcohols, respectively, by visible-light-mediated deoxygenation is described. Easily accessible monoallylated/propargylated substrates were activated either as inexpensive ethyl oxalates or as recyclable 3,5-bis(trifluoromethyl)benzoates to generate alkyl radicals suitable for 5-exo-trig/5-exo-dig cyclizations under visible-light irradiation.
RESUMO
A photo-redox-catalyzed procedure for the one-step formation of sultones from α,ω-alkenols and trifluoromethylsulfonyl chloride is described. Using [Cu(dap)2]Cl (1 mol %), a wide range of substrates can be cleanly converted to the target compounds, while commonly employed photoelectron transfer catalysts such as [Ru(bpy)3]Cl2 or fac-Ir(ppy)3 fail in this transformation. The obtained fluorinated sultones are attractive as potential electrolyte additives or as structural motifs in drug synthesis, with the latter being demonstrated with the synthesis of a trifluoroethyl-substituted analogue of a benzoxathiin that has high anti-arrhythmic activity.
