Intramolecular aminations of C-H bonds represent an elegant synthetic way to form important N-heterocycles. If suitable nitrene precursors are employed, organometallic complexes are able to catalyze ...the C-H amination under mild conditions. In the past years, Fe catalysis has emerged as a vigorously developing new (old) discipline. The present review highlights the most important developments in this field through a systematic differentiation between open-shell (radical) and closed-shell (non-radical) mechanisms.
The intramolecular Fe-catalyzed amination of C-H bonds using azides as nitrene precursors represents an elegant approach toward N-heterocycles. This review summarizes the most recent achievements while focussing on fundamental mechanistic aspects.
The nucleophilic iron complex Bu4NFe(CO)3(NO) (TBAFe) catalyzes the direct intramolecular C−H amination of α‐azidobiaryls and (azidoaryl)alkenes into the corresponding carbazoles and indoles, ...respectively, under mild conditions and with low catalyst loadings. These features and the broad functional‐group tolerance render this method a particularly attractive alternative to established noble‐metal‐based procedures.
The nucleophilic iron complex Bu4NFe(CO)3(NO) (TBAFe) catalyzes the selective intramolecular aryl/vinyl C(sp2)−H amination of aryl azides to give either substituted carbazole or indole derivatives in good to excellent yields. Kinetic isotope effects reveal a mechanistic similarity to the non‐catalyzed thermal and rhodium‐catalyzed variants.
The defined Fe hydride complex FeH(CO)(NO)(Ph(3)P)(2) is highly active as a catalyst for selective hydrosilylation of internal alkynes to vinylsilanes. Depending on the silane employed either E- or ...Z-selective hydrosilylation products were formed in excellent yields and good to excellent stereoselectivities.
The nucleophilic iron complex Bu4NFe(CO)3(NO) (TBAFe) catalyzes the direct intramolecular amination of unactivated C(sp3)−H bonds in alkylaryl azides, which results in the formation of substituted ...indoline and tetrahydroquinoline derivatives.
What a surprise: The anionic iron complex Bu4NFe(CO)3(NO) catalyzes the denitrogenative C(sp3)−H amination of a variety of alkylaryl azides to the corresponding indolines and, unexpectedly, tetrahydroquinolines in good yields.
A cycloisomerization of aryl allenyl ketones to 3-arylidene-indan-1-ones using a cationic Fe-complex as a catalyst is reported. The catalyst opens a synthetically interesting reaction pathway to this ...surprisingly underrepresented class of indanones that are not accessible using alternative catalytic systems.
Ironing out the kinks: A highly regioselective allylic alkylation can be performed in the presence of catalytic amounts of an iron(−II) complex and triphenylphosphane (see scheme; ...EWG=electron‐withdrawing group). Allyl carbonates and pronucleophiles are coupled in high yields with a high regioselectivity comparable only with that obtained with Rh catalysts. The reaction is broadly applicable and does not require external base.
The nucleophilic Fe complex Bu4NFe(CO)3(NO) (TBAFe) catalyzes the direct intramolecular amination of aryl vinyl azides to give the corresponding indole derivatives in good to excellent yields.
The ...anionic Fe complex Bu4NFe(CO)3(NO) catalyzes the denitrogenative C(sp3)–H amination of a variety of aryl vinyl azides to the corresponding indoles in good to excellent yields.
A method for the selective deuteration of polyfunctional organic molecules using catalytic amounts of RuCl2(PPh3)3 and D2O as a deuterium source is presented. Through variation of additives like CuI, ...KOH, and various amounts of zinc powder, orthogonal chemoselectivities in the deuteration process are observed. Mechanistic investigation indicates the presence of different, defined Ru‐complexes under the given specific conditions.
C−H activation: A method for the selective deuteration of polyfunctional organic molecules using catalytic amounts of RuCl2(PPh3)3 and D2O as a deuterium source is presented. Through variation of additives like CuI, KOH, and various amounts of zinc powder, orthogonal chemoselectivities in the deuteration process are observed (see scheme).
The chemoselective reduction of alkyne, ketones, or nitro groups using (Ph3P)3RuCl2 as an inexpensive catalyst and Zn/water as a stoichiometric reductant is reported. Depending on the nature of the ...additive and the temperature, good chemoselectivities were observed allowing, e.g., for the selective reduction of a nitro group in the presence of a ketone or an alkyne.
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