This review intends to provide an overview on the role of halide anions in the development of the research area of asymmetric anion-binding organocatalysis. Key early elucidation studies with chloride as counter-anion confirmed this type of alternative activation, which was then exploited in several processes and contributed to the advance and consolidation of anion-binding catalysis as a field. Thus, the use of the halide in the catalyst–anion complex as both a mere counter-anion spectator or an active nucleophile has been depicted, along with the new trends toward additional noncovalent contacts within the HB-donor catalyst and supramolecular interactions to both the anion and the cationic reactive species.

A complementary set of chiral N,N‐ligands enables the Pd‐catalyzed β‐C−H arylation of unbiased internal methylene groups in good yield and with high levels of enantio‐ and diastereoinduction. Both the dia‐ and enantioselectivity can be reversed, thus allowing the selective arylation of any of the four β‐C−H bonds in cycloalkanecarboxamides of various ring sizes. The method is applicable to a broad range of aryl iodides with electron‐withdrawing and ‐donating substituents in the o‐, m‐, or p‐position.

A nucleophile screening for the organocatalyzed enantioselective Reissert‐type dearomatization of quinoline derivatives using chiral triazoles as anion‐binding catalysts was realized. Our recently reported helical tetrakis(triazole) catalysts (TetraTri) have proven to be highly active in this type of reactions, however the methods were limited to nucleophiles with a N value of 10 according to the Mayr's nucleophilicity scale. In this study, different carbon‐nucleophiles of varied nucleophilicity N‐values were explored, allowing the identification of potential novel reaction partners with N >5 such as ketene thioacetals. Thus, a number of chiral 1,2‐dihydroisoquinoline‐thioesters with an enantioselectivity up to 92:8 er. were synthetized, which could easily be transformed into a more valuable amide derivative.

Herein, a solution phase NMR conformer population analysis is employed to probe the effect of remote electronic perturbations on the conformational equilibria of a series of para-substituted βfluorosulfides (1), sulfoxides (2) and sulfone derivatives (3). Conformations that allow for stabilizing stereoelectronic (σ C-H → σ* C-F) and electrostatic (F -•••S +) interactions predominate: this is consistent with the Sulfur-Fluorine Gauche Effect. The molar fractions (χ) of the two possible gauche conformers correlate linearly with the electron-withdrawing aptitude of the para-substituent, rendering the system ideally suited for a Hammett-type analysis. Despite the clear influence that the remote parasubstituents have on conformer population, this is superseded by the oxidation state on sulfur (II, IV, VI), where an increased preference for the gauche conformer follows the trend: sulfide < sulfone < sulfoxide. It is envisaged that this proof of concept in controlling conformer population, either by proximal (oxidation state) or remote tuning (para-substituent), will find application in molecular design.

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