Enantioselective Fluoroamination: 1,4‐Addition to Conjugated Dienes Using Anionic Phase‐Transfer Catalysis

Shunatona, Hunter P.; Früh, Natalja; Wang, Yiming; Rauniyar, Vivek; Toste, F. Dean

doi:10.1002/anie.201302002

Cited by 137 publications

(57 citation statements)

References 70 publications

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“…[4][5][6] Recently, asymmetric anionic phase-transfer reactions 7,8) have been reported using chiral phosphates with an aziridinium cation 9) and N-haloammonium cations. [10][11][12][13][14][15][16][17][18] …”

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confidence: 99%

Acceleration of Acid-Catalyzed Hydrolysis in a Biphasic System by Sodium Tetracyanocyclopentadienides

Sakai

Bito

Itakura

et al. 2016

CHEMICAL & PHARMACEUTICAL BULLETIN

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The hydrolysis of tert-butyldimethylsilyl L-menthyl ether (3) in a CH 2 Cl 2 -1 M HCl biphasic solvent system was accelerated by the addition of sodium tetracyanocyclopentadienides 1. Particularly, the reaction rate was enhanced using sodium salt 1a-c with a lipophilic substituent on the cyclopentadienide ring. From the results obtained by a triphasic experiment, hydrolysis proceeds via the formation of hydronium ion 2 in the aqueous phase by ion exchange, followed by the transfer of 2 to the CH 2 Cl 2 phase.Key words phase-transfer reaction; hydrolysis; tetracyanocyclopentadienide; acid-catalyzed reaction Phase-transfer reactions have garnered increasing attention in organic chemistry because of their mild, sustainable conditions. 1) Phase-transfer catalysts (PTCs) enhance the reactivity of anionic reagents by forming a lipophilic ion pair, mediating a reaction in the organic phase or at the interface between two phases. Enantioselective phase-transfer reactions catalyzed by chiral quaternary ammonium salts are one of the representative methods for synthesizing optically active molecules.2,3) Anionic PTCs have also been developed for reactions where lipophilic anions enhance the solubility of the reactive cationic species, thereby promoting the reactions. Kobayashi et al. have reported the first anionic phase-transfer reaction using tetrakis(3,5-bis(trifluoromethyl) phenyl) borate (TFPB) anion. [4][5][6] Recently, asymmetric anionic phase-transfer reactions 7,8) have been reported using chiral phosphates with an aziridinium cation 9) and N-haloammonium cations. [10][11][12][13][14][15][16][17][18]

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confidence: 99%

Acceleration of Acid-Catalyzed Hydrolysis in a Biphasic System by Sodium Tetracyanocyclopentadienides

Sakai

Bito

Itakura

et al. 2016

CHEMICAL & PHARMACEUTICAL BULLETIN

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“…7 Mechanistically, CDC reactions are proposed to proceed via initial substrate oxidation to a cationic, unsaturated intermediate ( 1 ) that undergoes subsequent inter- or intramolecular nucleophilic attack. 8 Given our group’s recent success in developing enantioselective halogenation reactions by exploiting chiral phosphate anion phase-transfer catalysis with cationic halogenating reagents, 9 we envisioned that a chiral phosphate ( 2 , Scheme 1B) could undergo anion exchange with an appropriately chosen cationic oxidant, ensuring that the phosphate would be in close proximity to form a tight ion-pair ( 3 ) with the substrate upon oxidation. Preferential attack on one of the prochiral faces of the resulting ionic complex would provide an enantioenriched product ( 4 ) and release the chiral phosphate.…”

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Asymmetric Cross-Dehydrogenative Coupling Enabled by the Design and Application of Chiral Triazole-Containing Phosphoric Acids

et al. 2013

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This report describes the development of an enantioselective C–N bond-forming reaction to produce 1,2,3,4-tetrahydroisoquinoline-derived cyclic aminals catalyzed by chiral phosphate anions. Central to the success of this goal was the design of a library of 3,3′-triazolyl BINOL-derived phosphoric acids capable of forming attractive hydrogen-bonding interactions with the peptide-like substrate. We envision this work will offer an alternative to the conventional strategy of increasing catalyst steric bulk to improve enantioselectivity with BINOL-derived phosphoric acids.

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“…Enantioselective fluoroaminocyclization of conjugated dienes by Toste et al 25 A close examination of the halocyclization reactions discussed so far revealed that, despite providing access to a large variety of chiral heterocycles, their scope with respect to the nucleophilic component remained rather narrow. For all these reactions, the nucleophiles were derivatives of acids, alcohols, or amines ( Figure 1).…”

Section: Methodsmentioning

confidence: 98%

Catalytic Enantioselective Halocyclizations beyond Lactones: Emerging Routes to Enantioenriched Nitrogenous Heterocycles

Tripathi

Mukherjee

2013

Synlett

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Electrophilic halogen-induced reactions of unactivated olefins are an important class of transformations, whose catalytic enantioselective variants have surfaced during the past few years as effective means of olefin heterodifunctionalization. This article covers important developments in the area of enantioselective halocyclizations, specifically in the context of the synthesis of nitrogenous heterocycles.Stereoselective functionalization of unactivated olefins is possibly the most sought-after strategy for generating diversity from easily accessible starting materials. In this regard, the catalytic asymmetric homofunctionalization of unactivated olefins might be considered as a successful and rather mature area of research, thanks to the discovery of methods for epoxidation, dihydroxylation, aziridination, and, to some extent, diamination. Heterodifunctionalization, on the other hand, remained a relatively less well explored territory. Electrophilic halogen-induced activation of olefins followed by nucleophilic addition is a remarkably general strategy for stereoselective olefin heterodifunctionalization (Scheme 1). 1 Halolactonization [Scheme 1 (B); Nu = CO 2 H] is the most prominent example in this category. Even though halolactonization was discovered more than a century ago 2 and has been applied to the synthesis of numerous natural and nonnatural targets, 3 the development of catalytic enantioselective halolactonization and related halocyclization reactions has proved notoriously difficult. Because proven approaches to asymmetric catalysis failed when applied to halocyclization reactions, the field of asymmetric halocyclization was, until recently, virtually unexplored, except for some sporadic examples involving chiral phase-transfer catalysts and chiral Lewis acids. 4 The past few years have witnessed a renaissance in the area of enantioselective olefin halofunctionalization. 5,6 As expected, halolactonization was the first such reaction to catch the attention of researchers, and a number of methods for highly enantioselective chloro-, bromo-, and iodolactonization reactions were developed with the help of a range of structurally dissimilar catalysts. 7 These reactions were not restricted to olefins, as conjugated enynes 8 and alkynes 9 were also subjected to enantioselective halolactonizations. From these reports, the mechanistic pictures associated with these reactions became clearer and a foundation was laid for further developments. Subsequently, several other halocyclization reactions joined the Chandra Bhushan Tripathi (left) received his B.Sc.Scheme 1 Electrophilic halogen-induced stereoselective olefin functionalization (A) and its intramolecular variant, halocyclization (B) SYNLETT 2014, 25, 0163-0169 Advanced online publication: 03.12.20130 9 3 6 -5 2 1 4 1 4 3 7 -2 0 9 6

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Enantioselective Fluoroamination: 1,4‐Addition to Conjugated Dienes Using Anionic Phase‐Transfer Catalysis

Cited by 137 publications

References 70 publications

Acceleration of Acid-Catalyzed Hydrolysis in a Biphasic System by Sodium Tetracyanocyclopentadienides

Acceleration of Acid-Catalyzed Hydrolysis in a Biphasic System by Sodium Tetracyanocyclopentadienides

Asymmetric Cross-Dehydrogenative Coupling Enabled by the Design and Application of Chiral Triazole-Containing Phosphoric Acids

Catalytic Enantioselective Halocyclizations beyond Lactones: Emerging Routes to Enantioenriched Nitrogenous Heterocycles

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