Proposal : Organokatalysatoren für die fluorige biphasische Katalyse ; Möglichkeiten der homogenen Katalyse mit anschließendem Katalysator‐Recycling

Übertragung des Konzeptes der fluorigen biphasischen Systeme bzw. Übergangsmetallkatalyse auf die fluorige biphasische Organokatalyse. Entwicklung neuer Organokatalysatoren für dieses neuartige Katalysekonzept auf der Basis bereits bekannter Taddol, Thioharnstoff und Binolphosphat-Katalysatoren. Synthese der vorgestellten fluorigen Organokatalysatoren. Einsatzgebiete, Katalysatorrecycling.A new Concept in Organocatalysis is presented. Fluorous biphasic Organocatalysis, derived from fluorous biphasic systems, is based on commonly used organocatalysts, such as taddol, thiourea, binol-phosphate.synthesis and design of catalysts as well as potential applications and recycling methods are presented

C-H Functionalization via Iron-Catalyzed Carbene-Transfer Reactions

The direct C-H functionalization reaction is one of the most efficient strategies by which to introduce new functional groups into small organic molecules. Over time, iron complexes have emerged as versatile catalysts for carbine-transfer reactions with diazoalkanes under mild and sustainable reaction conditions. In this review, we discuss the advances that have been made using iron catalysts to perform C-H functionalization reactions with diazoalkanes. We give an overview of early examples employing stoichiometric iron carbene complexes and continue with recent advances in the C-H functionalization of C(sp2)-H and C(sp3)-H bonds, concluding with the latest developments in enzymatic C-H functionalization reactions using iron-heme-containing enzymes

Photoinduced palladium-catalyzed 1,2-difunctionalization of olefins

Palladium-catalyzed cross-coupling reactions belong to the most important transformations for the construction of new C-C or C-heteroatom bonds. More recently, the photochemical activation of palladium complexes emerged as a key strategy to leverage palladium catalysis at room temperature beyond the scope of conventional cross-coupling chemistry. Herein, we report on the photoinduced, palladium-catalyzed 1,2-difunctionalization reaction of electron-rich olefins. Mechanistic experiments and computational studies reveal that this reaction proceeds via addition of an alkyl radical followed by a oxidation of a radical intermediate to access carbocation intermediates, which is inaccessible via classic thermal reaction conditions. The carbocation can then be applied to a variety of secondary C-C or C-heteroatom bond forming reactions. This strategy now allows a general approach towards densely functionalized unsymmetric 1,1-bis(heterocyclyl)alkanes

Photoinduced Palladium-Catalyzed 1,2-Difunctionalization of Electron-Rich Olefins via a Reductive Radical-Polar Crossover Reaction

Palladium-catalyzed cross-coupling reactions belong to the most important transformations for the construction of C–C or C-heteroatom bonds. More recently, the photochemical activation of palladium complexes emerged as a key strategy to leverage palladium catalysis at room temperature beyond the scope of conventional cross-coupling chemistry. Herein, we report on the photoinduced palladium-catalyzed 1,2-difunctionalization reaction of electron-rich olefins. Mechanistic experiments and computational studies reveal that this reaction proceeds via the addition of an alkyl radical, followed by the oxidation of a radical intermediate to access carbocation intermediates, which are inaccessible via classic thermal reaction conditions. The carbocation can then be applied to a variety of secondary C–C or C–N bond-forming reactions. This strategy now allows a general approach toward densely functionalized unsymmetric 1,1-bis(heterocyclyl)alkanes

Photoinduced Palladium-Catalyzed 1,2-Difunctionalization of Electron-Rich Olefins via a Reductive Radical-Polar Crossover Reaction

Palladium-catalyzed cross-coupling reactions belong to the most important transformations for the construction of C–C or C-heteroatom bonds. More recently, the photochemical activation of palladium complexes emerged as a key strategy to leverage palladium catalysis at room temperature beyond the scope of conventional cross-coupling chemistry. Herein, we report on the photoinduced palladium-catalyzed 1,2-difunctionalization reaction of electron-rich olefins. Mechanistic experiments and computational studies reveal that this reaction proceeds via the addition of an alkyl radical, followed by the oxidation of a radical intermediate to access carbocation intermediates, which are inaccessible via classic thermal reaction conditions. The carbocation can then be applied to a variety of secondary C–C or C–N bond-forming reactions. This strategy now allows a general approach toward densely functionalized unsymmetric 1,1-bis(heterocyclyl)alkanes

Intermolecular amination of allenes via twofold photocatalytic nitrene transfer reactions

The amination with monovalent, nitrogen-based intermediates constitutes an important reaction for the construction of valuable amines. The high basicity of reagents, reaction intermediates or products however poses significant challenges to metal-catalyzed amination through coordination and blocking of catalytically active sites and hampering their efficiency. In this context, high-yielding intermolecular amination reaction of allenes remain an unsolved challenge in organic synthesis and general methods are not available. Herein, we describe a photochemical approach towards the intermolecular amination of allenes via free nitrene radical anions as the key reactive intermediate. This reaction proceeds without the participation of catalyst-bound nitrogen species and can thus overcome current limitations. We report on the application in the amination of allenes to give azetidine and cyclopropyl amines with a broad and general substrate scope. Experimental and theoretical studies were performed to provide an understanding of the reaction mechanism and rationalize the high efficiency of this photocatalytic approach

Iron-Catalyzed C—H Insertions: Organometallic and Enzymatic Carbene Transfer Reactions

C—H insertion reactions with organometallic and enzymatic catalysts based on earth-abundant iron complexes remain one of the major challenges in organic synthesis. In this report, we describe the development and application of these iron-based catalysts in the reaction of two different carbene precursors with N-heterocycles for the first time. While FeTPPCl showed excellent reactivity in the Fe(III) state with diazoacetonitrile, the highest activities of the YfeX enzyme could be achieved upon heme-iron reduction to Fe(II) with both diazoacetonitrile and ethyl diazoacetate. This highlights unexpected and subtle differences in reactivity of both iron catalysts. Deuterium labeling studies indicated a C—H insertion pathway and a marked kinetic isotope effect. This transformation features mild reaction conditions, excellent yields or turnover numbers with broad functional group tolerance, including gram-scale applications giving a unique access to functionalized N-heterocycles.</p