Intramolecular diamination reactions are described which yield cyclic ureas as direct products of an oxidative alkene transformation in the presence of palladium acetate and iodosobenzene diacetate as terminal oxidant. The reaction is truly catalytic in metal catalyst and represents the proof of principle for this elusive type of alkene oxidation.

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A first palladium-catalyzed intramolecular diamination of unfunctionalized terminal alkenes has recently been reported. This study investigates the details of its mechanistic course based on NMR titration, kinetic measurements competition experiments, and deuterium labeling. It concludes a two-step procedure consisting of syn-aminopalladation with an unligated palladium(II) catalyst state followed by oxidation to palladium(IV) and subsequent C-N bond formation to give the final products as cyclic diamines. Related reactions employing sulfamides give rise to aminoalkoxy-functionalization of alkenes. This process was investigated employing deuterated alkenes and found to follow an identical mechanism where stereochemistry is concerned. It exemplifies the importance of cationic palladium(IV) intermediates prior to the final reductive elimination from palladium and proves that the nucelophile for this step stems from the immediate coordination sphere of the palladium(IV) precursor. These results have important implications for the general development of alkene 1,2-difunctionalization and for the individual processes of aminopalladation and palladium-catalyzed C(alkyl)-N bond formation.

Chiral aryliodine(III)r eagents have provided an advancedc oncept for enantioselective synthesis and catalysis.W ith the advent of chiral iodine(I/III) catalysis,m anyd ifferent structures have been explored in the area. Thec urrently most prominent catalyst design is based on ar esorcinol core and the attachment of two lactic side chainsb earing ester or amide groups.T his enables ap rivileged modular catalyst synthesis,i nw hich fine-tuning with respect to the specificr eaction requirement is straightforward. Thep resent overview summarizes the structural variation and optimization of such chiral aryliodine catalysts andd iscusses structural properties of the active iodine(III) catalyst states.T he status quo of enantioselective iodine(I/III) oxidation catalysis with respect to intramolecular and intermolecular reaction control is reviewed, and specific aspects of the individual catalytic cycles are discussed. 1I ntroduction 2C hiral Aryliodine Catalysts 3E nantioselective Catalysis 3.1 Catalytic DearomatizationReactions 3.2 Formal C(sp 3 )Functionalization 3.3 Difunctionalization of Alkenes 4C onclusionScheme 14. Aryliodine-catalyzede nantioselective intermolecular para-dearomatization of phenols and aniline.Scheme15. Aryliodine-catalyzed enantioselective intermolecular para-dearomatization by Maruoka.Scheme30. Catalytic enantioselective version of the aminofluorination reaction.Scheme 28. Enantioselectiveo xidative cyclization of w-alkenylcarboxylic acids.Scheme29. Catalytic intramolecular diaminationo fa lkenes.

ABSTRACT:Conditions for an attractive and productive protocol for the position-selective intramolecular C-H amination of aliphatic groups (Hofmann-Löffler reaction) are reported employing sulfonimides as nitrogen sources. N-Iodosuccinimide is the only required promoter for this transformation, which is conveniently initiated by visible light. The overall transformation provides pyrrolidines under mild and selective conditions as demonstrated for 17 different substrates.The intramolecular C-H amination of aliphatic groups has recently attracted significant interest from the synthetic community. Major work has focused on the identification of suitable transition metal catalysts to provide the aforementioned transformation. 1 Directed evolution of metalloproteins has recently emerged as a complimentary approach. 2 An alternative consists of the use of small organocatalysts 3 as non-metallic promoters, which, due to their capability to avoid metal contamination, is of major importance to fields such as biological and medicinal synthesis.From a historical perspective, the halide-mediated C-N bond formation at non-activated hydrocarbons was discovered over a century ago and is well established as the Hofmann-Löffler reaction. 4 The general conditions call for preformation of a halogenated amine, which upon irradiation in the presence of strong acid promotes C-H halogenation, which is usually followed by basemediated pyrrolidine formation. A useful modification providing significantly milder reaction conditions was introduced by Suarez, 5 who reported that Hofmann-Löffler-type cyclization reactions can be conducted in the presence of a mixture of molecular iodine and a hypervalent iodine reagent of the general structure ArI(O 2 CR) 2 . 6 This protocol was employed by Fan, who demonstrated its compatibility with sulfonamides as nitrogen sources. 7 We have recently demonstrated that this reaction can be conducted with catalytic amounts of iodine and the use of a single equivalent of hypervalent iodine(III) as the terminal oxidant. 8 This accomplishment has demonstrated that iodine catalysis is indeed feasible within the borders of the Hofmann-Löffler reaction, provided that the iodine concentration is maintained at a sufficient level to perpetuate the two intertwined catalytic cycles. However, the permanent requirement of using a hypervalent iodine reagent as a terminal oxidant 9 has triggered interest in whether the reaction could also be conducted with just a single amount of halide reagent as a stoichiometric promoter. Such a reaction would serve as an important addition to the existing protocols for Hofmann-Löffler reactions.

The influence of a 2-pyridinyl substituent on the catalytic performance of aryliodide as a catalyst in iodine(III) chemistry was explored. An efficient Lews-base adduct between the pyridine nitrogen and the electrophilic iodine(III) center was identified and confirmed by X-ray analysis. This arrangement was shown to generate a kinetically competent superior catalyst structure for the catalytic dioxygenation of alkenes. It introduces the concept of Lewis-base adduct formation as a kinetic factor in iodine(I/III) catalysis.

Metallfrei und asymmetrisch: Die erste enantioselektive Diaminierung von Styrolen benötigt lediglich ein chirales hypervalentes Iod(III)‐Reagens als Oxidationsmittel und Bismesylimid als Stickstoffquelle (siehe Schema, Ms=Methansulfonyl). Die Reaktion verläuft unter milden Bedingungen und ergibt hohe Enantiomerenüberschüsse.

Iodine catalysis was developed for aliphatic fluorination through light‐promoted homolytic C−H bond cleavage. The intermediary formation of amidyl radicals enables selective C−H functionalization via carbon‐centered radicals. For the subsequent C−F bond formation, previous methods have typically been limited by a requirement for electrophilic fluorine reagents. We here demonstrate that the intermediary instalment of a carbon–iodine bond sets the stage for an umpolung, thereby establishing an unprecedented nucleophilic fluorination pathway.