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International audience; Due to the omnipresence of chiral organofluorine compounds in pharmaceutical, agrochemical, and material chemistry, the development of enantioselective methods for their preparation is highly desirable. In the present study, the enantioselective organocatalyzed acylation of a,a-difluorohydrins using a commercially available chiral isothiourea is reported through a kinetic resolution (KR) process. It reveals that the difluoromethylene moiety (C(sp 3)F 2) can serve as a directing group through electrostatic fluorine-cation interactions, greatly improving the enantioselectivity of the KR. In this context, a broad range of fluorinated alcohols such as valuable 4,4-difluoro-1,3-diols could be synthesized with exquisite enantiocontrol (typically > 99:1 er). Turning to 2,2difluoro-1,3-diols, we also demonstrated that aromatic and fluorinated groups were mutually compatible to provide the expected enantioenriched adducts with > 99:1 er.

Oxylipins are formed in vivo from polyunsaturated fatty acids (PUFAs). A large structural variety of compounds is grouped under the term oxylipins, which differ from their formation mechanism (involving enzymes or not), as well as their chemical structures (cyclopentane, tetrahydrofuran, hydroxylated-PUFA, etc.). All structures of oxylipins are of great biological interest. Directly correlated to oxidative stress phenomenon, non-enzymatic oxylipins are used as systemic and/or specific biomarkers in various pathologies, and more especially, they were found to have their own biological properties. Produced in vivo as a non-separable mixture of isomers, their total synthesis is a keystone to answer biological questions. In this work, the total synthesis of three non-enzymatic oxylipins derived from docosahexaenoic acid (DHA) and docosapentanoic acid (DPAn-3) is described using a unique and convergent synthetic strategy.

The reactivity of phosphorus and sulfur ylides toward carbonyl compounds constitutes a well-known dichotomy that is a common educational device in organic chemistry─the former gives olefins, while the latter gives epoxides. Herein, we report a stereodivergent carbonyl olefination that challenges this dichotomy, showcasing thiouronium ylides as valuable olefination reagents. With this method, aldehydes are converted to

Thiyl radicals offer unique catalytic patterns for the direct covalent activation of alkenes. However, important limitations in terms of structural diversity and handling have hampered the routine use of thiyl radicals in covalent radical catalysis. Herein, we report a new class of cationic sulfur-centered radicals to achieve covalent radical catalysis. Their generation from highly modular thioureas by photoredox catalysis make their utilization very simple and reliable. The synthetic potential and the versatility of the catalytic system were finally evaluated in a (3+2)-radical cascade between vinylcyclopropanes and olefins.

Isothiouronium salts are easily accessible and stable compounds. Herein, we report their use as versatile deoxasulfenylating agents enabling a stereoselective, thiol-free protocol for synthesis of thioethers from alcohols. The method is simple, scalable and tolerates a broad range of functional groups otherwise incompatible with other methods. Late-stage modification of several pharmaceuticals provides access to multiple analogues of biologically relevant molecules. Performed experiments give insight into the reaction mechanism., A simple and scalable method for stereoselective synthesis of thioethers directly from alcohols using isothiouronium salts is presented. The utility of this thiol-free reaction was exemplified by late-stage modification of complex molecules.

International audience; A series of organic dyes derived from s-tetrazine have been synthesized, and their photophysical and electrochemical properties are systematically investigated. Testing these compounds as photoredox catalysts in a model oxidative C-S bond cleavage of thioethers has led us to identify new classes of active s-tetrazines. Moreover, some of them can be formed in situ from commercially available 3,6-dichlorotetrazine, making this photocatalyzed C-S bond functionalization simple and highly practical.

International audience

An efficient strategy for the synthesis of a variety of quinolin-2(1H)-one derivatives has been developed. The reaction proceeded from cinnamide derivatives via a tandem reaction in the presence of NaOH to afford the corresponding 2- quinolin-2(1H)-one derivatives in good to excellent yields.

International audience; A new organocatalytic and environmentally friendly aerobic oxidative-catalyzed nitroso-Diels-Alder (NDA) reaction of Narylhydroxylamines with dienecarbamates has been developed. 3,6-Bis(2,2,2-trifluoroethoxy)-s-tetrazine) was found to be an effective catalyst to selectively oxidize various N-arylhydroxylamines in the presence of molecular oxygen, but in the absence of photostimulation, as a terminal oxidant. In addition, active catalytic species can be generated in situ from commercially available 3,6-dichlorotetrazine.

This review covers recent developments relating to organocatalyzed transformations by chiral isothioureas (ITUs) since their original introduction by Birman in 2006. This class of nucleophilic heterocycles was first involved in anhydride activation in enantioselective acyl transfer reactions, but it was more recently shown that activation of other reagents was possible, considerably enlarging their number of catalytic enantioselective transformations. Four main modes of activation as Lewis bases can currently be listed: (1) acylisothiouronium intermediates involved in acyl transfer, (2) silylisothiouronium species involved in silyl transfer, (3) acylisothiouronium enolates involved in several concerted and formal pericyclic transformations, and (4) α,β-unsaturated acylisothiouronium species involved in domino transformations. This review is organized according to these different modes of activation of chiral isothioureas.

The cleavage of sulfidic C–S bonds under visible-light irradiation was harnessed to generate carbocations under neutral conditions and synthesize valuable di- and triarylalkanes as well as benzyl amines. To this end, photoredox catalysis and direct photoinduced C–S bond cleavage are used as complementary approaches and participate in the versatility of the general strategy. Extensive mechanistic studies have demonstrated the diversity of the reaction mechanism at work in these different reactions.

Traditionally employed in the synthesis of small ring systems and rearrangement chemistry, sulfur-based ylides occupy a unique position in the toolbox of the synthetic organic chemist. In recent years a number of pioneering researchers have looked to expand the application of these unorthodox reagents through the use of transition metal catalysis. The strength and flexibility of such a combination have been shown to be of key importance in developing powerful novel methodologies. This chapter summarises recent developments in transition metal-catalysed sulfonium/sulfoxonium ylide reactions, as well as providing a historical perspective. In overviewing the successes in this area, the authors hope to encourage others into this growing field.

International audience; Synthesis of biologically active molecules (whether at laboratory or industrial scale) remains a highly appealing area of modern organic chemistry. Nowadays, the need to access original bioactive scaffolds goes together with the desire to improve synthetic efficiency, while reducing the environmental footprint of chemical activities. Long neglected in the field of total synthesis, enantioselective organocatalysis has recently emerged as an environmentally friendly and indispensable tool for the construction of relevant bioactive molecules. Notably, enantioselective Brønsted acid catalysis has offered new opportunities in terms of both retrosynthetic disconnections and controlling stereoselectivity. The present report attempts to provide an overview of enantioselective total or formal syntheses designed around Brønsted acid-catalyzed transformations. To demonstrate the versatility of the reactions promoted and the diversity of the accessible motifs, this Minireview draws a systematic parallel between methods and retrosynthetic analysis. The manuscript is organized according to the main reaction types and the nature of newly-formed bonds.

Meso compounds represent a particular family of achiral molecules bearing elements of chirality. Their desymmetrization through enantioselective catalytic methods usually leads to elaborate chiral building blocks containing several stereogenic elements, which can be a very useful and elegant approach in the context of total synthesis. In the present review, the power of this strategy is illustrated through the different possibilities of catalytic enantioselective desymmetrization. From the combination of the hidden symmetry detection and the catalytic enantioselective transformations a new type of economy emerges: the economy of chiral reagents. 1 Introduction 1.1 What Is a Meso Compound? 1.2 Why Is the Catalytic Enantioselective Desymmetrization of Meso Compounds a Powerful Strategy in Total Synthesis? 1.3 Toward an Economy of Chiral Reagents 2 Enzymatic Desymmetrization 2.1 (–)-Sceptrin (Baran, 2006) 2.2 cis-Solamin (Stark, 2006) 2.3 Crocacin C (2010, Bressy/Pons) 3 Metallocatalyzed Desymmetrization 3.1 Quadrigemine C (2002, Overman) 3.2 (+)-Homochelidonine (2007, Lautens) 3.3 (–)-Cyanthiwigin F (2008, Stoltz) 3.4 [5]-Ladderanoic Acid (2016, Gonzalez-Martinez/Boxer/Burns) 4 Organocatalyzed Desymmetrization 4.1 (+)-Hirsutene (2008, List) 4.2 Alstoscholarines (2011, Neuville/Zhu) 4.3 (–)-Diospongin A (2015, Chuzel/Bressy) 5 Conclusion

Sulfur-based ylides have long been used for a number of classical transformations, in particular for the synthesis of small ring systems and various rearrangement reactions. By combining the unorthodox reactivity of such ylides with the strength and flexibility of transition-metal catalysis, a growing number of groups have in recent years looked to expand their application in organic synthesis. This chapter aims to summarise recent developments in transition-metal-catalysed sulfonium/sulfoxonium ylide reactions as well as to offer historical perspective. In overviewing the successes in this area, the authors hope to encourage others into this growing field.

International audience; The concept of a synergistic double catalytic kinetic resolution (DoCKR) as described in this article was successfully applied to racemic acyclic anti-1,3-diols, a common motif in natural products. This process takes advantage of an additive Horeau amplification involving two successive enantioselective organocatalytic acylation reactions, and leads to diesters and recovered diols with high enantiopurities. It was first developed with C 2-symmetrical diols and then further extended to non-C 2-symmetrical anti diols to prepare useful chiral building blocks. The protocol is highly practical as it only requires 1 mol % of a commercially available organocatalyst and leads to easily separable products. This procedure was applied to the shortest reported total synthesis of (+ +)-cryptocaryalactone, a natural product with anti-germinative activity.

This manuscript describes the convergent synthesis of aryl- and alkyl-disubstituted γ-pyrones from β-ketoacids. The reaction proceeds in the presence of trifluoromethanesulfonic anhydride via an unprecedented decarboxylative auto-condensation of the starting material. Herein, the scope and limitations of this transformation are reported. Graphical abstract