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Catalyst‐free 1,2‐carboboration of ynamides is presented. Readily available aryldichloroboranes react with alkyl‐ or aryl‐substituted ynamides in high yields with complete regio‐ and stereoselectivity to valuable β‐boryl‐β‐alkyl/aryl α‐aryl substituted enamides which belong to the class of trisubstituted alkenylboronates. The 1,2‐carboboration reaction is experimentally easy to conduct, shows high functional group tolerance and broad substrate scope. Gram‐scale reactions and diverse synthetic transformations convincingly demonstrate the synthetic potential of this method. The reaction can also be used to access 1‐boraphenalenes, a class of boron‐doped polycyclic aromatic hydrocarbons., The catalyst‐free direct 1,2‐carboboration of ynamides with readily available dichloroboranes is presented. Valuable α,β,β‐trisubstituted alkenylboronates are obtained in high yields with complete regio‐ and stereoselectivity under very mild conditions.

Light‐mediated coupling of acylsilanes with indoles is reported. This photo click reaction occurs under mild conditions (415 nm) mostly in quantitative yield and provides stable silylated N,O‐acetals via light mediated siloxycarbene generation with subsequent indole‐N‐H insertion. We show that this very efficient and fully atom economic coupling process can be applied to conjugate complex systems, as documented by the clicking of carbohydrates with indole alkaloids. The method is also applicable to the conjugation of polymer chains. The linking acetal moiety can be readily cleaved and it is also shown that wavelength‐selective coupling and cleavage with acyl silanes bearing a second photoactive moiety is possible. This is documented by a successful polymerization/depolymerization sequence and by a polymer folding/unfolding process., Visible‐light‐mediated coupling of acylsilanes with indoles is reported. This photoreaction occurs under mild conditions mostly in quantitative yield and provides stable silylated N,O‐acetals. The potential of the method is documented by the successful coupling of carbohydrates with indole alkaloids and by the conjugation of polymers.

α-C-H-functionalization of ketones and aldehydes has been intensively explored in organic synthesis. The functionalization of unactivated β-C-H bonds in such carbonyl compounds is less well investigated and developing a general method for their β-C-H arylation remains challenging. Herein we report a method that uses cooperative nickel and photoredox catalysis for the formal β-C-H arylation of aldehydes and ketones with (hetero)aryl bromides. The method features mild conditions, remarkable scope and wide functional group tolerance. Importantly, the introduced synthetic strategy also allows the β-alkenylation, β-alkynylation and β-acylation of aldehydes under similar conditions. Mechanistic studies revealed that this transformation proceeds through a single electron oxidation/Ni-mediated coupling/reductive elimination cascade.

Hydration of alkenes using first row transition metals (Fe, Co, Mn) under oxygen atmosphere (Mukaiyama‐type hydration) is highly practical for alkene functionalization in complex synthesis. Different hydration protocols have been developed, however, control of the stereoselectivity remains a challenge. Herein, highly diastereoselective Fe‐catalyzed anaerobic Markovnikov‐selective hydration of alkenes using nitroarenes as oxygenation reagents is reported. The nitro moiety is not well explored in radical chemistry and nitroarenes are known to suppress free radical processes. Our findings show the potential of cheap nitroarenes as oxygen donors in radical transformations. Secondary and tertiary alcohols were prepared with excellent Markovnikov‐selectivity. The method features large functional group tolerance and is also applicable for late‐stage chemical functionalization. The anaerobic protocol outperforms existing hydration methodology in terms of reaction efficiency and selectivity., The highly diastereoselective Fe‐catalyzed anaerobic Markovnikov‐selective hydration of alkenes using nitroarenes as oxygenation reagents is reported.

Oligosilanes are of great interest in the fields of organic photonics and electronics. In this communication, a highly efficient visible-light-mediated hydrosilylation of electron-deficient alkenes through cleavage of a trimethylsilyl-polysilanyl Si-Si bond is explored. These reactions smoothly occur on readily available organo(tristrimethylsilyl)silanes and other oligosilanes in the presence of an IrIII -based photo-redox catalyst under visible light irradiation. Silyl radicals are generated through single electron oxidation of the oligosilane assisted by the solvent. The introduced method exhibits broad substrate scope and high functional group tolerance with respect to the organo(tristrimethylsilyl)silane and alkene components, enabling the construction of functionalized trisilanes. In addition, this catalytic system can be also applied to highly strained bicyclo[1.1.0]butanes as silyl radical acceptors.

Cyclopropanes are an important class of building blocks in organic synthesis. Herein, a ring-opening/arylcarboxylation/acylation cascade reaction for the 1,3-difunctionalization of aryl cyclopropanes enabled by cooperative NHC and organophotoredox catalysis is reported. The cascade works on monosubstituted cyclopropanes that are in contrast to the heavily investigated donor/acceptor cyclopropanes more challenging to be difunctionalized. The key step is a radical/radical cross coupling of a benzylic radical generated in the photoredox catalysis cycle with a ketyl radical from the NHC catalysis cycle. The transformation features metal-free reaction conditions and tolerates a diverse range of functionalities.

Two‐component Giese type radical additions are highly practical and established reactions. Herein, three‐component radical conjugate additions of unactivated alkenes to Michael acceptors are reported. Amidyl radicals, oxidatively generated from α‐amido oxy acids using redox catalysis, act as the third reaction component which add to the unactivated alkenes. The adduct radicals engage in Giese type additions to Michael acceptors to provide, after reduction, the three‐component products in an overall alkene carboamination reaction. Transformations which can be conducted under practical mild conditions feature high functional group tolerance and broad substrate scope., Three in sequence! Three‐component radical conjugate addition of unactivated alkenes to Michael acceptors is reported. Oxidatively generated amidyl radicals act as the third reaction component which first add chemoselectively to the unactivated alkenes. The adduct radicals generated then react with the Michael acceptors to provide after reduction the three‐component products in an overall alkene carboamination reaction.

The reaction of readily generated silyl lithium reagents with various aryl fluorides to provide the corresponding aryl silanes is reported. DFT calculations reveal that the nucleophilic aromatic substitution of the fluoride anion by the silyl lithium reagent proceeds through concerted ipso substitution. In contrast to the classical nucleophilic aromatic substitution, this concerted ionic silyldefluorination also occurs on more electron-rich aryl fluorides.

A three‐component 1,2‐aminoarylation of vinyl ethers, enamides, ene‐carbamates and vinyl thioethers by synergistic photoredox and nickel catalysis is reported. 2,2,2‐Trifluoroethoxy carbonyl protected α‐amino‐oxy acids are used as amidyl radical precursors. anti‐Markovnikov addition of the amidyl radical to the alkene and Ni‐mediated radical/transition metal cross over lead to the corresponding 1,2‐aminoarylation product. The radical cascade, which can be conducted under practical and mild conditions, features high functional group tolerance and broad substrate scope. Stereoselective 1,2‐aminoarylation is achieved using a L‐(+)‐lactic acid derived vinyl ether as the substrate, offering a novel route for the preparation of protected enantiopure α‐arylated β‐amino alcohols. In addition, 1,2‐aminoacylation of vinyl ethers is achieved by using an acyl succinimide as the electrophile for the Ni‐mediated radical coupling., 1,2‐aminoarylation of vinyl ethers, enamides, ene‐carbamates and vinyl thioethers by synergistic photoredox and nickel catalysis is reported. The radical cascade features high functional group tolerance and broad substrate scope. Stereoselective 1,2‐aminoarylation is achieved as well as 1,2‐aminoacylation of vinyl ethers.

Radical 1,1,2-trifunctionalization of terminal alkynes by an addition-translocation-cyclization-trapping sequence using readily available alkynyl triflones as trifluoromethyl radical precursors and trapping reagents is reported. Cascades occur by addition of the trifluoromethyl radical to a terminal alkyne, 1,5-hydrogen atom transfer, 5-exo-cyclization, and subsequent alkynylation to provide (1-trifluoromethyl)propargyl cyclopentanes. Reactions proceed with commercial dibenzoyl peroxide or α,α'-azobisisobutyronitrile as the initiator at elevated temperature and provide the highly substituted cyclopentanes in good yields.

A metal‐free and direct alkene C−H cyanation is described. Directing groups are not required and the mechanism involves electrophilic activation of the alkene by a cyano iodine(III) species generated in situ from a [bis(trifluoroacetoxy)iodo]arene and trimethylsilyl cyanide as the cyanide source. This C−H functionalization can be conducted on gram scale, and for noncyclic 1,1‐ and 1,2‐disubstuted alkenes high stereoselectivity is achieved, thus rendering the method highly valuable.

A general and practical strategy for remote site-selective functionalization of unactivated aliphatic C-H bonds in various amides by radical chemistry is introduced. C-H bond functionalization is achieved by using the readily installed N-allylsulfonyl moiety as an N-radical precursor. The in situ generated N-radical engages in intramolecular 1,5-hydrogen atom transfer to generate a translocated C radical which is subsequently trapped with various sulfone reagents to afford the corresponding C-H functionalized amides. The generality of the approach is documented by the successful remote C-N3 , C-Cl, C-Br, C-SCF3 , C-SPh, and C-C bond formation. Unactivated tertiary and secondary C-H bonds, as well as activated primary C-H bonds, can be readily functionalized by this method.

A three-component transition-metal-free amidofluorination of unactivated alkenes and styrenes is presented. α-Amido-oxy acids are introduced as efficient and easily accessible amidyl radical precursors that are oxidized by a photoexcited organic sensitizer (Mes-Acr-Me) to the corresponding carboxyl radical. Sequential CO2 and aldehyde/ketone fragmentation leads to an N-centered radical that adds to an alkene. Commercial Selectfluor is used to trap the adduct radical through fluorine-atom transfer. The transformation features by high functional-group tolerance, broad substrate scope, and practical mild conditions. Mechanistic studies support the radical nature of the cascade.

Indolylboron ate complexes readily generated from 2-lithioindoles and boronic esters underwent multicomponent dearomative coupling with D-A cyclopropanes and alkyl halides in the presence of Sc(OTf)3 as a catalyst. The reactions proceeded with complete diastereoselectivity and excellent stereospecificity to provide indolines containing three contiguous stereocenters. The valuable boronic ester moiety remains in the product and allows for subsequent functionalization.

A method for site-specific intermolecular γ-C(sp3 )-H functionalization of ketones has been developed using an α-aminoxy acid auxiliary applying photoredox catalysis. Regioselective activation of an inert C-H bond is achieved by 1,5-hydrogen atom abstraction by an oxidatively generated iminyl radical. Tertiary and secondary C-radicals thus formed at the γ-position of the imine functionality undergo radical conjugate addition to various Michael acceptors to provide, after reduction and imine hydrolysis, the corresponding γ-functionalized ketones.

Transition‐metal‐free radical α‐perfluoroalkylation with the accompanying vicinal β‐alkenylation of unactivated alkenes is presented. These radical cascades proceed by means of 1,4‐ or 1,5‐alkenyl migration by electron catalysis on readily accessed allylic alcohols. The reactions comprise a regioselective perfluoroalkyl radical addition with subsequent alkenyl migration and concomitant deprotonation to generate a ketyl radical anion that sustains the chain as a single‐electron‐transfer reducing reagent.

The visible-light-promoted decarboxylation of α-imino-oxy propionic acids for the generation of iminyl radicals has been accomplished through the use of Ir(dFCF3 ppy)2 (dtbbpy)PF6 as a photoredox catalyst. Different from visible-light-promoted homolysis and single-electron reduction of oxime derivatives, this strategy provides a novel catalytic cycle for alkene carboimination through a sequence comprising N-radical generation, iminyl radical cyclization, intermolecular conjugate addition to a Michael acceptor, and single-electron reduction to afford various pyrroline derivatives in an overall redox-neutral process. The indolizidine alkaloid skeleton could be easily constructed from a pyrroline derivative prepared by this synthetic method.

Sn(OTf)2-catalyzed 1,3-aminobromination of donor-acceptor cyclopropanes with various sulfonyl amides or electron poor anilines and N-bromosuccinimide is reported. Reactions which are experimentally easy to conduct, occur with complete regio- and stereospecificity (for anilines) resulting in γ-aminated α-brominated malonic diesters which are obtained in good to excellent yields (up to 98%). These compounds are valuable substrates for follow-up chemistry to provide substituted azetidines and γ-lactams in high yields.

Eine effiziente Methode zur asymmetrischen intramolekularen Dearomatisierung von Indolen unter oxidativer Katalyse mit N-heterocyclischen Carbenen wird vorgestellt. Nutzliche, optisch aktive spirocyclische Indolenine mit quartarem Stereozentrum fallen dabei in exzellenten Ausbeuten und Stereoselektivitaten an. Die Indol-Ausgangsverbindungen sind leicht zuganglich, und die Reaktionen verlaufen uber eine intramolekulare Indolacylierung der 3-Position mit einem in situ erzeugten Acylazolium-Intermediat unter Bildung einer spirocyclischen Ketoneinheit.

An enantioselective three-component radical reaction of quinolines or pyridines with enamides and α-bromo carbonyl compounds by dual photoredox and chiral Bronsted acid catalysis is presented. A range of valuable chiral γ-amino-acid derivatives are accessible in high chemo-, regio-, and enantioselectivity from simple, readily available starting materials under mild reaction conditions. Using the same strategy, the asymmetric synthesis of 1,2-diamine derivatives is also reported.

The diversity-oriented desulfonylative functionalization of alkyl allyl sulfones with various sulfone-type reagents by radical chemistry has been developed. The readily installed allylsulfonyl moiety acts as a C-radical precursor, which is substituted by various functionalities using sulfur-based radical trapping reagents. The generality of this approach is documented by the successful desulfonylative alkynylation, azidation, trifluoromethylthiolation, sulfenylation, trifluoromethylselenylation, halogenation, and deuteration. The method is compatible with a wide range of functional groups. Considering the deuteration, products are obtained in good yields with a high level of deuterium incorporation.

Die Reaktion von in situ erzeugten Arinen mit Vinylsulfiden liefert benzanellierte Schwefelylide in einer (3+2)-Cycloaddition. Die intermediar auftretenden Ylide lassen sich mit Elektrophilen abfangen (uber Protontransfer oder durch erneute Arinaddition) und nach anschliesender β-Eliminierung mit hoher Stereoselektivitat in di-, tri- oder tetra-substituierte Alkene uberfuhren. Experimentelle Untersuchungen und DFT-Rechnungen beleuchten den Mechanismus dieser Kaskadenreaktion.

Eine neue und einfache Methode zur Herstellung von funktionalisierten Chinoxalinen wird vorgestellt. Ausgehend von leicht zuganglichen ortho-Diisocyanarenen und (Perfluor)alkyliodiden wird das Chinoxalin-Gerust uber eine radikalische Atom-Transfer-Additionsreaktion aufgebaut, um 2-Iod-3-(perfluor)alkylchinoxaline zu erhalten. Diese Radikalkaskade kann sowohl durch sichtbares Licht als auch durch α,α′-Azobisisobutyronitril (AIBN) initiiert werden. Die Methode liefert gute Ausbeuten (bis 94 %) und lasst sich auch im grosen Masstab leicht durchfuhren. Folgechemie zeigt den Nutzen dieser neuen radikalischen Chinoxalin-Synthese auf.

B(C6F5)2-containing boryldienes 4 underwent the addition of two molar equivalents of TEMPO to give N,O-bonded four-membered heterocyclic products 7. The reaction is a metal-free example of the generation of reactive nitrogen-centered TEMPO radical derivatives, in this case by the addition of TEMPO to the borane, followed by carbon-nitrogen bond formation and subsequent trapping of the resulting allyl radical by the second equivalent of TEMPO.