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Recent developments in isocyanide based multicomponent reactions in applied chemistry

Multicomponent reactions (MCRs) are fundamentally different from two-component reactions in several aspects. Among the MCRs, those with isocyanides have developed into popular organic-chemical reactions in the pharmaceutical industry for the preparation of compound libraries of low-molecular druglike compounds. With a small set of starting materials, very large libraries can be built up within a short time, which can then be used for research on medicinal substances. Due to the intensive research of the last few years, many new backbone types have become accessible. MCRs are also increasingly being employed in the total synthesis of natural products. MCRs and especially MCRs with isocyanides offer many opportunities to attain new reactions and basic structures. However, this requires that the chemist learns the “language” of MCRs, something that this review wishes to stimulate.

Multicomponent Reactions with Isocyanides.

N-Heterocyclic carbenes have become universal ligands in organometallic and inorganic coordination chemistry. They not only bind to any transition metal, be it in low or high oxidation states, but also to main group elements such as beryllium, sulfur, and iodine. Because of their specific coordination chemistry, N-heterocyclic carbenes both stabilize and activate metal centers in quite different key catalytic steps of organic syntheses, for example, C-H activation, C-C, C-H, C-O, and C-N bond formation. There is now ample evidence that in the new generation of organometallic catalysts the established ligand class of organophosphanes will be supplemented and, in part, replaced by N-heterocyclic carbenes. Over the past few years, this chemistry has been the field of vivid scientific competition, and yielded previously unexpected successes in key areas of homogeneous catalysis. From the work in numerous academic laboratories and in industry, a revolutionary turning point in oraganometallic catalysis is emerging.

http://aether.cmi.ua.ac.be/artikels/Artikels%20Gitte/Artikels/Reviews/NHC-%20liganden%20Herrmann.pdf

N-heterocyclic carbenes: a new concept in organometallic catalysis.

Self-Assembly of Discrete Cyclic Nanostructures Mediated by Transition Metals

Methyltrioxorhenium(VII) forms air and moisture stable trigonal-bipyramidal adducts with several organometallic Lewis bases having a pyridine nitrogen atom as the donor moiety. These complexes have been isolated and fully characterised. A single-crystal structure of one of the products has been determined. Whilst the Re–N interaction is weaker than in some simple organic Lewis base adducts of Re(CH3)O3, e.g. with pyridine or 4-tert-butylpyridine, the more pronounced stability of the complexes described in this work is probably due to steric crowding and the moderate donor capability of the organometallic ligands. The donor capability of the ligands applied increases in the order Re(CO)3Br(4,4′-bpy)2 < 1,1′-bis(4-pyridylethynyl)ferrocene < ferrocenyl-4-pyridylacetylene.

Syntheses and characterisation of methyltrioxorhenium adducts of low-valence organometallic Lewis bases

Metal Complexes in Biology and Medicine, V. — New Bismuth Hydroxycarboxylate Complexes. Synthesis and Structure of Bismuth(III) Malate Monohydrate and Bismuth(III) Tartrate Trihydrate



Reaction of Bi(NO3)3 · 5 H2O with L-(–)-malic acid results in the formation of bismuth(III) malate monohydrate Bi[O2CCH2CH(O)CO2] · H2O (1) containing the tridentate ligand [L-(–)-malate]3– with all donating functions deprotonated. By way of contrast, reaction of Bi(NO3)3 · 5 H2O with L-(+)-tartraic acid gives bismuth(III) tartrate trihydrate (2), in which two different tartrate ligands, [L-(+)-tartrate]1– and [L-(+)-tartrate]2– are present. The solid-state structures have been determined by single-crystal X-ray methods and confirmed by powder diffraction measurements. The structure analyses exhibit a three-dimensional network in the crystalline state resulting from bridging and chelating properties of the polydentate hydroxycarboxylate ligands. Bismuth shows high coordination numbers.

Metallkomplexe in Biologie und Medizin, V. Neue Hydroxycarboxylat‐Komplexe von Bismut. Synthese und Struktur von Bismut(III)‐malat‐monohydrat und Bismut(III)‐tartrat‐trihydrat

Mehrfachbindungenzwischen Hauptgruppenelementen und Übergangsmetallen

Mehrfachbindungen zwischen Hauptgruppenelementen und Übergangsmetallen: LXVI. Zur Reaktivität von Hexahydrido(η5-pentamethylcyclopentadienyl)rhenium(VII), (η5-C5Me5)ReH6

Eberhardt Herdtweck

Papers

Syntheses and characterisation of methyltrioxorhenium adducts of low-valence organometallic Lewis bases

Metallkomplexe in Biologie und Medizin, V. Neue Hydroxycarboxylat‐Komplexe von Bismut. Synthese und Struktur von Bismut(III)‐malat‐monohydrat und Bismut(III)‐tartrat‐trihydrat

Mehrfachbindungenzwischen Hauptgruppenelementen und Übergangsmetallen

Mehrfachbindungen zwischen Hauptgruppenelementen und Übergangsmetallen: LXVI. Zur Reaktivität von Hexahydrido(η5-pentamethylcyclopentadienyl)rhenium(VII), (η5-C5Me5)ReH6

Mehrfachbindungen zwischen „nacktem”︁ Blei und übergangsmetallen – ein erstes Beispiel