Bond Forming Reactions Involving Isocyanides at Diiron Complexes

Abstract

The versatility of isocyanides (CNR) in organic chemistry has been tremendously enhanced by continuous advancement in transition metal catalysis. On the other hand, the urgent need for new and more sustainable synthetic strategies based on abundant and environmental-friendly metals are shifting the focus towards iron-assisted or iron-catalyzed reactions. Diiron complexes, taking advantage of peculiar activation modes and reaction profiles associated with multisite coordination, have the potential to compensate the lower activity of Fe compared to other transition metals, in order to activate CNR ligands. A number of reactions reported in the literature shows that diiron organometallic complexes can effectively assist and promote most of the “classic” isocyanide transformations, including CNR conversion into carbyne and carbene ligands, CNR insertion, and coupling reactions with other active molecular fragments in a cascade sequence. The aim is to evidence the potential offered by diiron coordination of isocyanides for the development of new and more sustainable synthetic strategies for the construction of complex molecular architectures.

Antiproliferative and bactericidal activity of diiron and monoiron cyclopentadienyl carbonyl complexes comprising a vinyl‐aminoalkylidene unit

“…[18,20,21] resonances, attributed to the E isomer with reference to the N-substituents, in analogy with what detected for the parent vinyliminium compounds and for 5a and 5h in the solid state (see X-ray diffraction studies), the only exception being 5g (E and Z isomers in 5:1 relative ratio). In the NMR spectra of 6a-c, the two methyl groups are nonequivalent, in agreement with the partial doublebond nature of C 1 -N, for instance they resonate at 51.8 and 44.0 ppm in the 13 C spectrum of 6c. The aminoalkylidene character of C 1 is reflected by a typical lowfield resonance (256.4-265.6 ppm).…”

“…NMR spectra were recorded at 298 K on a Bruker Avance II DRX400 instrument equipped with a BBFO broadband probe. Chemical shifts (expressed in parts per million) are referenced to the residual solvent peaks [33] ( 1 H, 13 C) or to external . NMR spectra were assigned with the assistance of 1 H-13 C (gs-HSQC and gs-HMBC) correlation experiments.…”

“…This represents a highly versatile scaffold to build functionalized bridging ligands, exploiting reaction routes which are commonly unavailable to mono-metal species, thanks to the cooperative effects supplied by the two adjacent iron centers. [13,14] Piano-stool carbonyl mononuclear derivatives are obtained via fragmentation of Fe 2 Cp 2 (CO) 4 , promoted by oxidative [2,15a] and reductive pathways, [16] or via addition of suitable donors. [17] Recently, we reported a preliminary study on the anticancer potential of diiron complexes with a bridging C 3 ligand supported on the [Fe 2 Cp 2 (CO) 2 ] frame, [18] alternatively described as vinyliminium or vinyl-aminoalkylidene ( Figure 1a).…”

Construction of a Functionalized Selenophene‐Allylidene Ligand via Alkyne Double Action at a Diiron Complex

“…The interest of some of us in the construction of functionalized organometallic structures, since almost 20 years ago, has been focused on diiron complexes,[11c], which constitute a matter of growing interest for several reasons. First, the dinuclear system offers the opportunity for reactivity patterns which are not available to similar monoiron species, as also mentioned above.…”

Silver-Assisted Oxidative Isocyanide Insertion of Ethers: A Direct Approach to β-Carbonyl α-Iminonitriles

“…Isocyanides have shown a wide variety of applications as versatile building blocks in organic synthesis, medicinal chemistry, and materials science . Over the past few decades, extensive effects have been devoted to the development of multicomponent reactions involving isocyanides for the synthesis of nitrogen-containing heterocycles .…”