Recent Developments in Enantioselective Metal‐Catalyzed Domino Reactions

Abstract

This review collects the very recent developments in enantioselective metal-catalyzed domino reactions published since the beginning of 2016. It illustrates that many types of enantioselective metal-catalyzed domino processes continue to be developed, allowing an easy one-pot access to complex molecular architectures from simple starting materials taking economic advantages, such as avoiding costly protecting groups and timeconsuming purification procedures after each step. 1 Introduction 2 Enantioselective Silver-Catalyzed Domino Reactions 3 Enantioselective Scandium-and Yttrium-Catalyzed Domino Reactions 4 Enantioselective Iron-Catalyzed Domino Reactions 5 Enantioselective Cobalt-Catalyzed Domino Reactions 6 Enantioselective Magnesium-Catalyzed Domino Reactions 7 Enantioselective Zirconium-Catalyzed Domino Reactions 8 Enantioselective Rhodium-Catalyzed Domino Reactions 9 Enantioselective Palladium-Catalyzed Domino Reactions 10 Enantioselective Copper-Catalyzed Domino Reactions 11 Enantioselective Domino Reactions Catalyzed with Other Metals 12 Conclusions IntroductionAsymmetric metal catalysis constitutes a powerful tool to highly enantioselectively perform many types of reactions. [1] In particular, the combination of asymmetric metal catalysis with the concept of domino reactions has allowed high molecular complexity to be easily achieved with remarkable levels of stereocontrol on the basis of simple economic one-pot procedures. In the last decade, many types of enantioselective domino processes, including multicomponent ones, [2] have been successfully catalyzed by a wide variety of chiral metal complexes. [3] Introduced by Tietze, the concept of domino reactions consists in one-step two or more bond-forming transformations occurring under the same reaction conditions. [4] A range of complex densely functionalized chiral molecules, including natural and/or biologically important products, have already been synthesized through these processes without requiring the purification of intermediates. [5] The goal of this review is to collect the very recent advances in enantioselective metal-catalyzed domino reactions published since the beginning of 2016 since this field was most recently updated this year, covering the literature until the end of 2015 (including only 2 references from 2016). [6] It is divided into ten parts, dealing successively with enantioselective silver-catalyzed domino reactions, scandium-and yttrium-catalyzed domino reactions, iron-catalyzed domino reactions, cobalt-catalyzed domino reactions, magnesium-catalyzed domino reactions, zirconium-catalyzed domino reactions, rhodium-catalyzed domino reactions, palladium-catalyzed domino reactions, copper-catalyzed domino reactions and enantioselective domino reactions catalyzed by other metals. Enantioselective Silver-Catalyzed Domino ReactionsRelated to its moderate Lewis acidity, silver has long been neglected in catalysis. However, many highly efficient transformations, [7] including enantioselective domino reactions, [8] are today availabl...

Photoinduced Decarboxylative Amino‐Fluoroalkylation of Maleic Anhydride

“…We found that both halogenated alkane and triethylamine hadt he same quenching effect on the photosensitizer,b ut the quenching coefficient of halogenated alkane (K SV (ICF 2 CO 2 Et), 0.6 mm À1 ) was much larger than that of triethylamine (K SV (Et 3 N), 0.05 mm À1 ), so halogenated hydrocarbon might be the major quenching agent.Ar eaction quantum yield was measured to be f= 3.2%,i ndicating the radicalc hain mechanism is less likely.B ased on above results, ap lausible mechanism is outlined in Figure 1. Photoexcitationo f[ Ru(bpy) 3 Cl 2 ]·6H 2 Ou pon blue irradiation resultsi nametal-to-ligand charge transfer (MLCT) exciteds tate. [11] Then difluoroalkyl radicali sg enerated througho xidative quenching.…”

“…[2] In this regard, transition-metal-catalyzed multicomponent reactions prove to be an ideal technology.A voidingt he synthesis of starting material, in as ingle operation, severaln ew bonds are formed and new functionalities are introduced. [3] In the meantime,i ncorporation of fluorinea toms into organic motifs has asignificant influence on the lipophilicity,metabolic stability, and bioavailability of organic molecules. [4] Fluoroalkylation using relativelym ild fluoroalkylh alides as af luorine source has been the focus of current research.…”

“…Our investigations began with [Ru(bpy) 3 Cl 2 ]·6H 2 Oa sthe photocatalyst. The targeted product could be obtained in 14 % yield by using three equivalents of ethyl difluoroiodoacetate, two equivalentso fm aleic anhydride,o ne equivalento fa niline and two equivalents of sodium hydrogen carbonate as ab ase (Table 1, entry 1).…”

“…Our attempts to explore other heteronucleophiles including hydroxy,t hiol, and phenylhydrazine were not successful under the current reaction conditions. [Ru(bpy) 3 Cl 2 ]6 H 2 OE t 3 N( 10.0) THF 71 17 [c] [Ru(bpy) 3 Cl 2 ]6 H 2 OE t 3 N( 8.0) THF 23 18 [d] [Ru(bpy) 3 Cl 2 ]6 H 2 OE t 3 N( 8.0) THF 41 19 [e] [Ru(bpy) 3 Cl 2 ]6 H 2 OE t 3 N( 8.0) THF 22 20 [f] [Ru(bpy) 3 Cl 2 ]6 H 2 OE t 3 N( 8.0) THF 15 21 -Et 3 N( 8.0) THF N.D. 22…”

“…[Ru(bpy) 3 Cl 2 ]6 H 2 O-THF N.D. 23 [g] [Ru(bpy) 3 Cl 2 ]6 H 2 OE t 3 N( 8.0) THF N.D. 24 [h] [Ru(bpy) 3 Chem. Eur.J.2020, 26,419 -422 www.chemeurj.org…”