Hypervalent Iodine Reagents DOI: 10.1002/anie.201206420 Defined Hypervalent Iodine(III) Reagents Incorporating Transferable Nitrogen Groups: Nucleophilic Amination through Electrophilic Activation** JosØ A. Souto, Claudio Martínez, Irene Velilla, and Kilian MuÇiz* Direct oxidative amination reactions of hydrocarbons are of high synthetic importance as they have no or little precedence in nature. [1] Processes of this type that proceed under metal- free conditions are particularly desirable owing to their environmental benigness and practicability. In principle, hypervalent iodine(III) reagents with their high oxidation potential are a promising concept for oxidative amination. [2] In examples in the area, mainly by Domínguez and co- workers, a reagent combination consisting of amides and PhI(O 2 CCF 3 ) 2 was used ; an intermediate A with an I ÀN bond was postulated, which generates an electrophilic nitrogen source upon heterolytic dissociation. [3] Despite their obvious synthetic utility, little information has been uncovered on the structural basis of the intermediary iodine reagents. Recently, a series of metal-free amination reactions of compounds with unfunctionalized carbon–hydrogen bonds have become available. These include direct aromatic ami- nation, [4] and the oxidative transfer of phthalimide to benzylic positions and aromatic rings. [5] The involvement of inter- mediate B with an iodine–nitrogen single bond as a precursor to nitrogen radicals or electrophiles has been suggested in the latter cases. However, definite structural proof could not be obtained for this putative intermediate. [6] In a striking accom- plishment, Ochiai isolated the hypervalent bromine(III) reagent 1, which is attacked by alkenes at the s*NÀBr orbital and even undergoes direct C ÀH amination of alkanes at room temperature. [7, 8] In general, hypervalent iodine(III) species containing I ÀN single bonds are rare. [9, 10] More importantly from a synthetic standpoint, isolated hypervalent iodine(III) reagents bearing a defined I À N single bond with a transferable nitrogen group for metal-free amination reactions of hydrocarbons are extremely scarce and no general reactivity has been described so far. In recent work, [11] we reported unusual metal-free diamination, and allylic and acetylenic amination reactions based on a new hypervalent iodine(III) reagent of the type PhI(OAc)N(SO 2 R) 2 . We now describe the synthesis and isolation of unprecedented hypervalent iodine species of the formula PhI[N(SO 2 R) 2 ] 2 , discuss their formation and their solid-state and solution structures, and report unparalleled chemical transformations based on electrophilic activation/ nucleophilic amination with these reagents. We recently found that iodosobenzene diacetate under- goes protonolysis in the presence of bistosylimide leading to loss of acetic acid and to immediate formation of the monomeric species 2a. [11a] However, we noticed that for the diamination of styrene as a standard transformation, the isolated compound 2a promoted only a slow reaction. More- over, addition of a second equivalent of bistosylimide is required for a quantitative transformation. As a consequence, we anticipated that 2a is not the active reagent, but rather a precursor to it. Indeed, in the presence of water, 2a is converted into the new m-oxo-bridged compound 3 (Scheme 1). This product is also obtained directly from iodosobenzene diacetate upon treatment with bistosylimide and water. This formation of 3 is a fast process as monitored by in situ IR spectroscopy. Characteristic IR bands at 1714 cm À1 confirm the presence of 2a as a short-living intermediate during the formation of 3. [12, 13] Compound 3 is an active reagent in the diamination of styrene ; however, as only two bistosylimido units are present, it gives a maximum yield of 50 % together with iodosoben- zene as the remaining iodine(III) species. Treatment of 3 with an additional two equivalents of bistosylimide leads to further chemical transformation and to the clean formation of the new monomeric iodine(III) compound 4, which incorporates two bisimido groups (Scheme 1). The solid-state structure of 4 is depicted in Figure 1. [12] It displays comparably short I À N distances of 2.210 , owing to the required stabilization of the electrophilic iodine center. Compound 4 indeed represents the elusive active reagent in the diamination of alkenes. [11a–c] When the initial conversion of styrene was monitored, the relative rate of the reaction [*] Dr. J. A. Souto, Dr. C. Martínez, Dr. I. Velilla, Prof. Dr. K. MuÇiz Institute of Chemical Research of Catalonia (ICIQ) Av. Països Catalans 16, 43007 Tarragona (Spain) E-mail: kmuniz@iciq.es Homepage: http://www.iciq.es Prof. Dr. K. MuÇiz Catalan Institution for Research and Advanced Studies (ICREA) Pg. Lluís Companys 23, 08010 Barcelona (Spain) [**] We thank Fundación ICIQ and the Spanish Ministerio de Economía (CTQ2011-25027) for financial support. Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/anie.201206420. . Angewandte Communications 1324  2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Angew. Chem. Int. Ed. 2013, 52, 1324 –1328