New palladium(II)–phthalimidato complexes have been synthesized, isolated, and structurally characterized. As demonstrated from over 30 examples, they constitute superior catalysts for oxidative amination reactions of alkenes with phthalimide as the nitrogen source. This work streamlines vicinal difunctionalization of alkenes and provides access to significantly improved and experimentally simplified synthetic protocols.

An intramolecular approach towards the regioselective construction of 2,3-diarylated indoles is reported. The reaction follows an intramolecular electrophilic N−H and C−H bond functionalization between the aniline and acetylene. This methodology employs the concept of a traceless tether to provide access to the free 2,3-diarylated indole products comprising a total of 18 examples. Hypervalent iodine reagents were identified as suitable promoters and four different protocols are provided, including stoichiometric and catalytic transformations.

Molecular structures of the most prominent chiral non-racemic hypervalent iodine(III) reagents to date have been elucidated for the first time. The formation of a chirally induced supramolecular scaffold based on a selective hydrogen-bonding arrangement provides an explanation for the consistently high asymmetric induction with these reagents. As an exploratory example, their scope as chiral catalysts was extended to the enantioselective dioxygenation of alkenes. A series of terminal styrenes are converted into the corresponding vicinal diacetoxylation products under mild conditions and provide the proof of principle for a truly intermolecular asymmetric alkene oxidation under iodine(I/III) catalysis.

Die Molekülstrukturen der gegenwärtig besten chiralen, nichtracemischen hypervalenten Iod(III)-Reagentien wurden zum ersten Mal aufgeklärt. Die induzierte Bildung einer chiralen supramolekularen Struktur basierend auf Wasserstoffbrücken liefert eine Erklärung für die konsequent hohen asymmetrischen Induktionen mit diesen Reagentien. Ihr Anwendungsbereich wurde auf die enantioselektive Dioxygenierung von Alkenen erweitert. Eine Reihe von terminalen Styrolen wurde entsprechend unter milden Bedingungen in die Produkte der vicinalen Diacetoxylierung überführt. Bei dieser Umwandlung handelt es sich um die erste intermolekulare asymmetrische Oxidation von Alkenen unter Iod(I/III)-Katalyse.

A photochemical catalytic amination of arenes is presented. The reaction proceeds under benign iodine catalysis in the presence of visible light as the initiator and provides access to a range of differently substituted arylamines. A total of 29 examples demonstrate the broad applicability of this mild oxidation method. The scope of the reaction could further be expanded to silyl-tethered derivatives, which undergo intramolecular amination upon formation of seven-membered heterocycles. Cleavage of the silicon tether provides access to the corresponding 3-substituted anilines.

A computational study of the mechanism for the iodine(III)-mediated oxidative amination of alkenes explains the experimentally observed substrate dependence on product distribution. Calculations with the M06 functional have been carried out on the reaction between PhI(N(SO₂Me)₂)₂ and three different representative substrates: styrene, α-methylstyrene, and (E)-methylstilbene. All reactions start with electrophilic attack by a cationic PhI(N(SO₂Me)₂)⁺ unit on the double bond, and formation of an intermediate with a single C−I bond and a planar sp² carbocationic center. The major path, leading to 1,2-diamination, proceeds through a mechanism in which the bissulfonimide initially adds to the alkene through an oxygen atom of one sulfonyl group. This behavior is now corroborated by experimental evidence. An alternative path, leading to an allylic amination product, takes place through deprotonation at an allylic C−H position in the common intermediate. The regioselectivity of this amination depends on the availability of the resonant structures of an alternate carbocationic intermediate. Only in cases where a high electronic delocalization is possible, as in (E)-methylstilbene, does the allylic amination occur without migration of the double bond.

Iodine reagents have been identified as economically and ecologically benign alternatives to transition metals, although their application as molecular catalysts in challenging CH oxidation reactions has remained elusive. An attractive iodine oxidation catalysis is now shown to promote the convenient conversion of carbon–hydrogen bonds into carbon–nitrogen bonds with unprecedented complete selectivity. The reaction proceeds by two interlocked catalytic cycles comprising a radical chain reaction, which is initiated by visible light as energy source. This unorthodox synthetic strategy for the direct oxidative amination of alkyl groups has no biosynthetic precedence and provides an efficient and straightforward access to a general class of saturated nitrogenated heterocycles.

Iodreagentien werden als ökonomisch und ökologisch ansprechende Alternativen zu Übergangsmetallen aufgefasst, obgleich ihr Einsatz als molekulare Katalysatoren in anspruchsvollen C-H-Oxidationen weitgehend ausgeblieben ist. Hier wird eine attraktive Iodoxidationskatalyse vorgestellt, die eine bequeme Umwandlung von Kohlenstoff-Wasserstoff- in Kohlenstoff-Stickstoff-Bindungen mit bislang unerreichter vollständiger Selektivität ermöglicht. Die Reaktion verläuft innerhalb zweier miteinander verflochtener Katalysezyklen, die eine durch sichtbares Licht als Energiequelle initiierte Radikalkettenreaktion einschließen. Diese unorthodoxe Synthesestrategie zur direkten oxidativen Aminierung von Alkanen hat keine biosynthetischen Vorbilder und eröffnet einen effizienten und direkten Zugang zu gesättigten Stickstoffheterocyclen.

A copper(II)-mediated diamination of 1,3-butadienes is reported. The reaction employs an inorganic base, copper dibromide as a reagent, and saccharin as the nitrogen source. The diamination proceeds for a series of 1,3-butadienes under relatively mild conditions with complete selectivity in favor of the 1,4-oxidation products.

A new metal-free method for the rapid and productive preparation of indoles has been developed. This process is based on sterically congested hypervalent iodine compounds of the family of Koser reagents, and iodosobenzene in combination with 2,4,5-tris-isopropylbenzene sulfonic acid provides the highest yields and fastest reaction times. This reagent alone promotes the chemoselective oxidative cyclization of 2-amino styrenes to indoles in high yields under mild conditions.

Eine neue Methode unter metallfreien Bedingungen zur schnellen und produktiven Synthese von Indolen wurde entwickelt. Dieser Prozess beruht auf einer voluminösen Iodverbindung der Familie der Koser-Reagentien, wobei die Kombination aus Iodosobenzol und 2,4,5-Tris(isopropyl)benzolsulfonsäure die höchsten Ausbeuten und kürzesten Reaktionszeiten gewährleistet. Dieses Reagens vermittelt die chemoselektive oxidative Cyclisierung von 2-Vinylanilinen zu Indolen in hohen Ausbeuten und unter milden Reaktionsbedingungen.

Hypervalent iodine(III) reagents have been known for over a century, and their reaction profile is still actively investigated. Recent years have seen impressive improvements in the area of alkene difunctionalization reactions, where new methodologies have become available. Especially chiral non-racemic hypervalent iodine(III) reagents and catalysts have emerged as versatile tools for the realization of important enantioselective transformations.

Durante el último siglo se han estudiado en profundidad los reactivos de iodo(III) en diversas reacciones, estando vigente el interés en su reactividad. Actualmente se han producido importantes avances en el área de las reacciones de difuncionalización de alquenos, convirtiéndose estos reactivos y catalizadores de iodo(III) en poderosas herramientas, especialmente en su versión quiral para el desarrollo de transformaciones enantioselectivas.

Oxidation of a series of defined palladium(II) complexes bearing a bidentate ligand, and a methyl and an amidato substituent was carried out with the aim to gain a better understanding of the inherent requirements for CN bond-formation from Pd complexes in high oxidation state. This work clarified the role of the individual nitrogen sources and has important implication for alkylnitrogen bond-forming reactions catalyzed by Pd.

A rapid and productive vicinal diamination of alkenes takes place in the presence of a hypervalent iodine(III) reagent and bissulfonimides as nitrogen sources. A total of more than 60 examples are presented. The reaction is characterized by its robustness and its wide substrate scope: it proceeds selectively with both terminal and internal alkenes and tolerates a range of functional groups.

Se presenta un método eficiente y rápido para llevar a cabo la diaminación de alquenos promovido por especies de iodo(III) hipervalente en presencia de bissulfonilimidas. Una serie de mas de 60 olefinas, tanto en posición terminal como interna, con distinta sustitución demuestran la robustez del método y la elevada tolerancia a grupos funcionales.

Homogeneous palladium catalysis enables a novel intermolecular regioselective diamination of allylic ethers, which offers a convenient entry into 1,2,3-trisubstituted products. These represent suitable building blocks with differently protected nitrogen atoms for subsequent synthetic application.

Recent years have seen the rapid development of a new field of palladium catalysis in organic synthesis. This chemistry takes place outside the usually encountered Pd⁰/Pd^II cycles. It is characterized by the presence of strong oxidants, which prevent further palladium(II)-promoted reactions at a given point of the catalytic cycle by selective metal oxidation. The resulting higher-oxidation-state palladium complexes have been used to develop a series of new synthetic transformations that cannnot be realized within conventional palladium catalysis. This type of catalysis by palladium in a higher oxidation state is of significant synthetic potential.