Organic molecules bearing hypervalent iodine moieties have fascinated chemists over the years. Mild reaction conditions and environmentally friendly behavior through replacement of toxic heavy metals have led to their recent renaissance in organic synthesis. [1] Their use not only as selective oxidants [2] but also as enantiomerically pure reagents [3] make them versatile reagents for many organic transformations, such as the oxidation of sulfides to sulfoxides, [4] the a-oxygenation [5] and a-arylation of carbonyl compounds, [6] the dearomatization of phenols, [7] and the dioxygenation, [8] diamination, [9] aminohydroxylation, [10] and aminofluorination [11] of alkenes. The nature of hypervalent iodine(III) compounds to react as electrophiles and then act as excellent leaving groups make them highly suitable reagents for generating cationic intermediates, which can either directly react with nucleophiles or lead to rearranged products [12] under ring expansion, [13] ring contraction, [14] or aryl migration. [8d, 15] Similar rearrangements have been performed with much more toxic thallium reagents. [16] We recently reported a novel oxidative rearrangement of aryl substituted unsaturated carboxylic acids for the facile access of furanones. [17] Calculations were conducted to investigate the interplay of various cationic intermediates. Other studies have also confirmed the involvement of aryl moieties in cationic intermediates of rearrangement reactions. [18] The use of chiral hypervalent iodine reagents in asymmetric rearrangement reactions seems to be a very promising area of research and, to our knowledge, no reactions of this type have been reported to date. Herein, we describe the first stereoselective rearrangements of aryl substituted alkenes with high enantioselectivites mediated by chiral hypervalent iodine reagents. We have investigated chalcones of type 1, which are easily accessible through an aldol condensation between methyl ketones RCOMe and aryl aldehydes ArCHO. Oxidative rearrangements of such compounds to a-arylated carbonyl compounds have been known for some time. [19] The reaction of aryl-substituted alkenes 1 with electrophilic chiral iodine reagents results in the formation of phenyliodinated intermediates 2, which can be stabilized by the formation of phenonium ions [20] followed by the reaction with a second alcohol nucleophile to give the 1,2-migration products 3 (Scheme 1).Initially the reaction of (E)-1,3-diphenyl prop-2-en-1-one 1 a with only (diacetoxyiodo)benzene [PhI(OAc) 2 ] was investigated, but its reactivity with 1 a is too low and no conversion was observed (Table 1, entry 1). As already described, [19] an activation of the hypervalent iodine(III) reagent is necessary, and addition of 50 % aqueous H 2 SO 4 as a Brønsted acid to the reaction mixture [21] resulted in the rearranged product in 64 % yield. When using [bis(trifluoroacetoxy)iodo]benzene as an iodine(III) source, the yield increased to 82 % (Table 1, entries 2 and 3). Scheme 1. Rearrangement of 1 to 3 via ph...

Vicinal diamines constitute one the most important functional motif in organic chemistry because of its wide occurrence in a variety of biological and pharmaceutical molecules. We report an efficient metal‐free, highly stereoselective intramolecular diamination using a novel chiral hypervalent iodine reagent together with its application as an efficient catalyst for the synthesis of diamines.

The first stereoselective version of an iodine(III)-mediated rearrangement of arylketones in the presence of orthoesters is described. The reaction products, α-arylated esters, are very useful intermediates in the synthesis of bioactive compounds such as ibuprofen. With chiral lactic acid-based iodine(III) reagents product selectivities of up to 73 % ee have been achieved.

Organische Moleküle mit hypervalenten Iodsubstituenten haben Chemiker über Jahre hinweg fasziniert. Ihre milden Reaktionsbedingungen sowie ihre Umweltverträglichkeit durch die Vermeidung von toxischen Schwermetallen haben in jüngster Zeit zu einer Renaissance dieser Verbindungen in der organischen Synthese geführt. [1] Nicht nur ihre Verwendung als selektive Oxidationsmittel, [2] sondern auch als enantiomerenreine Reagentien [3] macht sie zu vielseitigen Reagentien für viele Umsetzungen wie die Oxidation von Sulfiden zu Sulfoxiden, [4] für a-Oxygenierungen [5] und a-Arylierungen von Carbonylverbindungen, [6] Desaromatisierungen von Phenolen, [7] Dioxygenierungen, [8] Diaminierungen, [9] Aminohydroxylierungen [10] und Aminofluorierungen [11] von Alkenen. Die Eigenschaft hypervalenter Iod(III)-Verbindungen, zunächst als Elektrophil und dann als ausgezeichnete Abgangsgruppe zu fungieren, macht diese Reagentien sehr geeignet zur Erzeugung kationischer Zwischenstufen, die entweder direkt mit Nukleophilen oder unter Ringerweiterung, [12] Ringverengung [13] oder Arylverschiebung [8d, 14] zu umgelagerten Produkten [15] reagieren kçnnen. Vergleichbare Umlagerungen kçnnen auch mit viel giftigeren Thalliumverbindungen durchgeführt werden. [16] Wir berichteten kürzlich über eine neuartige oxidative Umlagerung von arylsubstituierten ungesättigten Carbonsäuren als einfachen Zugang zu Furanonen. [17] Zur Untersuchung der verschiedenen kationischen Intermediate wurden Rechnungen durchgeführt. Andere Studien haben ebenfalls die Beteiligung von Aryleinheiten in kationischen Intermediaten von Umlagerungen bestätigt. [18] Der Einsatz chiraler hypervalenter Iodreagentien in asymmetrischen Umlagerungsreaktionen scheint ein recht vielversprechendes Forschungsgebiet zu sein, allerdings wurden unseres Wissens bisher noch keine derartigen Reaktionen beschrieben. Hier stellen wir die erste hoch enantioselektive, durch chirale hypervalente Iodreagentien vermittelte Umlagerung von Arylalkenen vor. Wir haben dazu Chalkone 1 untersucht, die Schema 1. Umlagerung von 1 zu 3 über Intermediat 2 durch hypervalente Iodreagentien Ar*IL 2 .

The cyclization of malonate derivatives by using hypervalent iodine(III) reagents is described. In this reaction, double bonds are dioxygenated to give five‐membered lactones in up to 70 % yield with diastereomeric ratios of up to 11:1.