The frontispiece shows the transformation of Fischer Carbene Complexes in a wide variety compounds through Higher-order Cycloadditions. flask, containing carbene, pour on paper different products synthesized last 20 years. In background, blackboard draws traces important contributions area, such as orbital correlation diagrams for Cycloadditions and representation molecular orbitals made by Woo...

Photolysis of ethyl diazomalonyl trypsin and of ethyl diazomalonyl chymotrypsin, followed by hydrolysis, yields several products. One of the major products has now been identified as S-carboxymethylcysteine. Since neither trypsin nor chymotrypsin contains an -SH bond, the reaction must involve cleavage of a disulfide bond by the carbene generated on photolysis. The products so far identzed from...

A new chloroform adduct of the N-heterocyclic carbene (NHC) 1,3-bis(2,6diisopropylphenyl)imidazolidin-2-ylidene (SIPr) has been prepared via C–H bond activation of the chloroform at the carbene carbon. This redox product was crystallized and was characterized by 1H and 13C-NMR spectroscopy, elemental analysis (EA), and single-crystal X-ray diffraction. The 1H and 13C-NMR spectroscopic data are ...

The reactions of two nucleophilic palladium carbene complexes with the strong Lewis acid B(C6F5)3 afforded two zwitterionic products. One of them features a remote nucleophilic attack at the para-carbon of the supporting ligand, while the other indicates C-F activation of B(C6F5)3. Both behaviours are reminiscent of the reactivity of frustrated Lewis pairs due to the steric inaccessibility of t...

The synthesis of the bulky 1-(1-arylimino-2,2-dimethylpropyl)-3-(aryl)imidazolium salt from the corresponding imidazole and the activated imidoyl chloride is presented. The absence of acidic protons adjacent to the iminic carbon allowed for the first isolation of an imino-N-heterocyclic carbene of this ligand class. The free carbene was isolated, structurally characterised, and coordinated to t...

In the crystal structure of the title compound, [Ag(3)Cl(C(8)H(15)N(3))(6)]Cl(2), the Ag(I) ion, which is located on a twofold rotation axis, exists in a T-shape coordination environment. Two carbene C atoms of the N-heterocyclic carbene (NHC) ligands are bonded tightly forming a slightly bent [Ag(NHC)(2)](+) cation [C-Ag-C angle = 162.80 (18)°]. Three of these complex cations are further aggre...

Transition metal-catalyzed transfers of carbenes, nitrenes, and oxenes are powerful methods for functionalizing C=C and C-H bonds. Nature has evolved a diverse toolbox for oxene transfers, as exemplified by the myriad monooxygenation reactions catalyzed by cytochrome P450 enzymes. The isoelectronic carbene transfer to olefins, a widely used C-C bond-forming reaction in organic synthesis, has no...

A study on the mechanism of the asymmetric intramolecular Stetter reaction is reported. This investigation includes the determination of the rate law, kinetic isotope effects, and competition experiments. The reaction was found to be first order in aldehyde and azolium catalyst or free carbene. A primary kinetic isotope effect was found for the proton of the aldehyde. Taken together with a seri...

A dinuclear N-heterocyclic carbene (NHC) copper complex efficiently catalyzes azide-alkyne cycloaddition (CuAAC) "click" reactions. The ancillary ligand comprises two 4,5-dimethyl-1,3-thiazol-2-ylidene units and an ethylene linker. The three-step preparation of the complex from commercially available starting compounds is more straightforward and cost-efficient than that of the previously descr...

Suitably designed, hydrophilic Fischer carbene complexes reduce HAuCl4 to produce stable gold nanoparticles localized on proteins in aqueous buffer solution.