Enantioselective Iodine(I/III) Catalysis in Organic Synthesis, Which Has Been Published in Final Form At

"This is the peer reviewed version of the following article: Enantioselective Iodine(I/III) Catalysis in Organic Synthesis, which has been published in final form at https://doi.org/10.1002/adsc.201800521 . This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving http://olabout.wiley.com/WileyCDA/Section/id-820227.html “ Enantioselective Iodine(I/III) Catalysis in Organic Synthesis Andrea Flores,a Eric Cots,a Julien Bergès,a and Kilian Muñiza,b* a Institute for Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science, Av. Països Catalans 16, 43007 Tarragona, Spain Fax: +34 977 920 224. E-mail: [email protected] b ICEA Passeig Lluís Companys, 23, 08010 Barcelona, Spain Abstract. Chiral aryliodine(III) reagents have provided an advanced concept for enantioselective synthesis and catalysis. Keywords: Chirality; Enantioselective Synthesis; With the advent of chiral iodine(I/III) catalysis, a large Homogeneous Catalysis; Iodine; Oxidation number of different structures have been explored in the area. The currently most prominent catalyst design is based on a resorcinol core and the attachment of two lactic side chains bearing ester or amide groups. It enables a privileged modular catalyst synthesis, in which fine-tuning with respect to the specific reaction requirement is straightforward. The present overview summarizes the structural variation and optimization of such chiral aryliodine catalysts and discusses structural properties of the active iodine(III) catalyst states. The 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. by virtue of their low toxicity, commercial availability, 1 Introduction high stability towards atmospheric oxygen and moisture, ease of recovery, easy handling and versatile Organic chemistry relies on homogeneous asymmetric [9] catalysis as an important working horse for the reactivity. With the goal of providing greener production of single enantiomers, which have a major synthetic solutions to the field of oxidation reactions, hypervalent iodine compounds have witnessed a impact in biomedical and pharmaceutical sciences. st [9] Due to this unparalleled importance of massive growth in the 21 century. The accomplishment of rendering them catalytic has enantiomerically pure compounds, conceptually new [10] endeavors to their synthetic availability are of utmost broadened their scope further. One of the importance and immediate interest. Within this predominant current aims of these reagents is context, the traditional concept of man-made complementing or replacing heavy-metal catalysts. homogeneous oxidation catalysis has been based on Iodine oxidants offer a high potential for the improvement of known reactions and the development the use of redox-active metals.[1] In this area, the identification and development of suitable chiral of new synthetic transformations. Their nature as ligands[2-4] has played a major role in order to polyvalent electrophiles and mild oxidants provides is complemented by their environmental benignness that accomplish defined, kinetically dominating reaction circumvents the problem of toxicity mainly associated pathways involving effective enantiodiscrimination.[4] Such an approach is largely reminiscent of Nature’s to the use of some transition metals. Common concept of metalloproteins,[5] which have generated a successful approaches are based on the use of versatile pool of oxygenation reactions. Their scope aryliodine(I) derivatives, which can be readily has recently been significantly expanded through oxidized to iodine(III) under the required reaction conditions. For enantioselective transformations, the directed evolution.[6] The advent of organocatalysis [7] has provided an additional class of small organic catalyst design strategy is comparable to conventional molecules that can be brought into play for transition metal catalysis, in which ionic and/or coordinative bonding of ligands is usually optimized homogeneous oxidation.[8] They can provide complementary reactivity pathways with respect to with regard to electronic and stereochemical properties transition metals. Within the class of metal-free small (Figure 1). For aryliodines, the chiral arene substituent is covalently bound. organic oxidants hypervalent iodine reagents have been widely applied in organic synthesis as oxidants 1 Andrea Flores was born in 1994 in Cerdanyola del Vallès, Barcelona (Spain). She studied Chemistry at the Autonomous University of Barcelona (Spain), where she obtained her MSc in 2017. She joined the group of Professor Muñiz at ICIQ in the fall of 2018. Her PhD work Figure 1. Main concepts for design of homogeneous centers around the development catalysts: transition metal and aryliodine(III) catalysts. of chiral aryliodine catalysts. Èric Cots was born in 1994 in 2 Chiral Aryliodine Catalysts Manresa, Barcelona (Spain). After completing his bachelor degree in chemistry at the Institut Suitable chiral iodine(III) structures have been Químic de Sarrià (URL), he identified to a large extent. Following the general moved to University of advent of iodine(III) reagents as important synthetic Barcelona where he obtained his tools, enantioselective reaction control has been MSc in Organic chemistry. devised following the principal aspect of introducing Currently he works at ICIQ in Professor Muñiz’s group as a chirality elements into the aryl substituent. Their PhD student, where he is application in enantioselective synthesis has been developing new reactions with reviewed previously.[11] Although the resulting chiral chiral iodine catalysis. reagents have found significant application, the synthesis of preformed iodine(III) centers can in some Julien Bergès was born in cases be cumbersome. Clearly, a catalytic reaction Toulouse (France) in 1989 and course, in which the active iodine(III) is repeatedly graduated in Chemistry at the generated in situ, represents the superior approach Ecole Supérieure de Chimie Organique et Minérale from economic and practicability standpoint. Within (Compiègne, France). In October this context, non-racemic iodoarenes(I) have been 2013 he began his PhD in the extensively developed since 2008 in order to arrive at laboratory of Dr. Taillefer at homogeneous catalytic performances. With respect to Ecole Nationale Supérieure de such chiral aryliodine(I) catalysts, all major sources of Montpellier and received its PhD degree in 2016 submitting a chirality have been investigated comprising central thesis on the functionalisation of chirality, axial chirality and helical chirality. aromatics rings by formation of C-C and C-N bonds catalysed by copper, iron or under transition metal -free. In July 2017, he joined the group of Professor Muñiz at R2 OMe ICIQ as postdoctoral researcher. HisAuthor current Portrait)) research focused on the development of methodologies for R t I 1 Cl SO2 Bu intermolecular C-H amination by electrophilic halide I I I N reagents R2 I 1 2 3 4 Kilian Muñiz was born in 1970 in Hildesheim (Germany). He studied Chemistry at the R Universities of Hannover I I O I OR* (Germany) and Oviedo (Spain) R* R* R R* R* N and at Imperial College (UK) and R earned his Doctorate in Organic I n Chemistry for work with 5 6 7 8 Professor Bolm at RWTH Aachen (Germany) in 1998. He Figure 2. Representative structures of chiral aryliodine(I) carried out postdoctoral research catalysts. with Professor Noyori at Nagoya University (Japan), before starting his independent research at Bonn University (Germany) with Professor Dötz (2001-2005). From 2006 to 2009 he held a position as Full Professor at the University of Strasbourg (France), where he was also a member of the Institut Universitaire de France. He moved to Spain in 2009 to join ICIQ in Tarragona (Spain) as a group leader and became ICREA Professor in 2010. His research interests include the Author Portrait)) 2 development of new catalysts for general use in oxidative Figure 3. Toolbox approach towards modular iodoarene amination and diamination reactions of hydrocarbons. structures of the resorcinol/lactate nature. This concept has been proven highly successful due to One of the first examples of a chiral iodine catalyst 1 the fact that structural fine-tuning of the catalysts can was developed by Kita and subsequently extended by be easily accomplished. The underlying modular Zhang (Figure 2). It contains an electrophilic iodine approach consists in condensation of the center and a carbon-based spiro-cyclic backbone with corresponding 2-iodo resorcinol cores with lactic acid [12] defined chirality. The privileged C2-symmetric derivatives and implementation of the ester and amide biaryl motif has also turned out useful as initially function. A related conceptual toolbox is based on the shown for compounds 2 and 3 by Quideau, followed functionalization of the central resorcinol moiety with by further developments from Einhorn and Kita.[13] vicinal N-acylated aminoalcohols. Although this The stereochemical action of lesser popular C1- approach should provide a similarly attractive entry symmetric structures has also been explored in the into catalyst diversification, compounds of type 12 architecture of iodoarenes and remains one of the most have so far been explored to a lesser extent. used to the day for aryliodine catalysts. These catalysts The major important feature of the

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