Bidentate Chiral Bis(imidazolium)-Based Halogen Bond Donors: Synthesis and First Applications in Enantioselective Recognition and Catalysis

2019 ◽  
Author(s):  
Revannath L. Sutar ◽  
Elric Engelage ◽  
Raphael Stoll ◽  
Stefan Huber
Keyword(s):  
Lewis Acids ◽  
Chiral Recognition ◽  
Halogen Bond ◽  
Halogen Bonding ◽  
Noncovalent Interaction ◽  
Asymmetric Induction ◽  
Nmr Studies ◽  
Lewis Bases ◽  
First Case ◽  
Mukaiyama Aldol

Even though halogen bonding – the noncovalent interaction between electrophilic halogen substituents and Lewis bases – has now been established in molecular recognition and catalysis, its use in enantioselective processes is still very little explored. Herein, we present the synthesis of chiral bidentate halogen bond donors based on two iodoimidazolium units with rigidly attached chiral sidearms. With these Lewis acids, chiral recognition of a racemic diamine is achieved in NMR studies. DFT calculations support a 1:1 interaction of the halogen bond donor with both enantiomers and indicate that the chiral recognition is based on a different spatial orientation of the Lewis bases in the halogen bonded complexes. In addition, moderate enantioselectivity is achieved in a Mukaiyama aldol reaction with a preorganized variant of the chiral halogen bond donor. This represents the first case in which asymmetric induction was realized with a pure halogen bond donor lacking any additionally active functional groups.

Bidentate Chiral Bis(imidazolium)-Based Halogen Bond Donors: Synthesis and First Applications in Enantioselective Recognition and Catalysis

2019 ◽  
Author(s):  
Revannath L. Sutar ◽  
Elric Engelage ◽  
Raphael Stoll ◽  
Stefan Huber
Keyword(s):  
Lewis Acids ◽  
Chiral Recognition ◽  
Halogen Bond ◽  
Halogen Bonding ◽  
Noncovalent Interaction ◽  
Asymmetric Induction ◽  
Nmr Studies ◽  
Lewis Bases ◽  
First Case ◽  
Mukaiyama Aldol

Even though halogen bonding – the noncovalent interaction between electrophilic halogen substituents and Lewis bases – has now been established in molecular recognition and catalysis, its use in enantioselective processes is still very little explored. Herein, we present the synthesis of chiral bidentate halogen bond donors based on two iodoimidazolium units with rigidly attached chiral sidearms. With these Lewis acids, chiral recognition of a racemic diamine is achieved in NMR studies. DFT calculations support a 1:1 interaction of the halogen bond donor with both enantiomers and indicate that the chiral recognition is based on a different spatial orientation of the Lewis bases in the halogen bonded complexes. In addition, moderate enantioselectivity is achieved in a Mukaiyama aldol reaction with a preorganized variant of the chiral halogen bond donor. This represents the first case in which asymmetric induction was realized with a pure halogen bond donor lacking any additionally active functional groups.

Applications of halogen bonding in solution

2015 ◽  
Vol 87 (1) ◽  
pp. 15-41 ◽  
Author(s):  
Andreas Vargas Jentzsch
Keyword(s):  
Halogen Atom ◽  
Halogen Bond ◽  
Halogen Bonding ◽  
Solvent System ◽  
Noncovalent Interaction ◽  
Solution Phase ◽  
Anion Binding ◽  
Lewis Bases ◽  
The Past ◽  
Catalytic Applications

AbstractHalogen bonding is the noncovalent interaction where the halogen atom acts as an electrophile towards Lewis bases. Known for more than 200 years, only recently it has attracted interest in the context of solution-phase applications, especially during the last decade which was marked by the introduction of multitopic systems. In addition, the small yet rich collection of halogen-bond donor moieties that appeared in this period is shown to be versatile enough as to be applied in virtually any solvent system. This review covers the applications of halogen bonding in solution during the past ten years in a semi-comprehensive way. Emphasis is made on molecular recognition, catalytic applications and anion binding and transport. Medicinal applications are addressed as well with key examples. Focussing on the major differences observed for halogen bonding, as compared to the ubiquitous hydrogen bonding, it aims to contribute to the design of future solution-phase applications.

Halogen-bond geometry: a crystallographic database investigation of dihalogen complexes

2003 ◽  
Vol 59 (4) ◽  
pp. 512-526 ◽  
Author(s):  
Carole Ouvrard ◽  
Jean-Yves Le Questel ◽  
Michel Berthelot ◽  
Christian Laurence
Keyword(s):  
Solid State ◽  
Lewis Acids ◽  
Halogen Bond ◽  
Lone Pair ◽  
Halogen Bonding ◽  
Lewis Acidity ◽  
Lewis Bases ◽  
Significant Relationships ◽  
Geometrical Features ◽  
Bonded Complexes

X-ray crystal structures of 141 halogen-bonded complexes Y—X...B formed between homo- and heteronuclear dihalogens Cl2, Br2, I2, IBr and ICl with O, S, Se, N, P and As Lewis bases show remarkable and constant geometrical features. The metrics of the halogen bond found in the gas phase for simple complexes [Legon (1999a). Angew Chem. Int. Ed. Eng. 38, 2686–2714] is supported (i) in the solid state, (ii) for new Lewis acids (I2 and IBr), (iii) for new basic centers (Se, As and =N—) and (iv) for more complicated bases. The Y—X...B arrangement is more linear than the corresponding Y—H...B hydrogen bond and the axis of the Y—X molecule lies in the plane of the B lone pair(s), with a preference for the putative lone-pair direction within that plane. However, exceptions to this lone-pair rule are found for sterically hindered thiocarbonyl and selenocarbonyl bases. A bond-order model of the halogen bond correctly predicts the observed correlation between the shortening of the X...B distance and the lengthening, Δd(Y—X), of the Y—X bond. The expectation that the solid-state geometric parameters d(X...B) and Δd(Y—X) reflect the strength of the interaction is supported by their significant relationships with the solution thermodynamic parameters of Lewis acidity and basicity strength, such as the Gibbs energy of 1:1 complexation of Lewis bases with diiodine. This analysis of halogen-bonded complexes in the solid state reinforces the similarities already known to exist between hydrogen and halogen bonding.

scholarly journals Catalytic Activation via π –Backbonding in Halogen Bonds?

2020 ◽  
Author(s):  
Andrew Wang ◽  
Pierre Kennepohl
Keyword(s):  
Halogen Bond ◽  
Halogen Bonding ◽  
Lewis Base ◽  
Computational Studies ◽  
Halogen Bonds ◽  
Covalent Interaction ◽  
Lewis Bases ◽  
Chemical Catalysis ◽  
Catalytic Activation

The role of halogen bonding (XB) in chemical catalysis has largely involved using XB donors as Lewis acid activators to modulate the reactivity of partner Lewis bases. We explore a more uncommon scenario, where a Lewis base modulates reactivity via a spectator halogen bond interaction. Our computational studies reveal that spectator halogen bonds may play an important role in modulating the rate of S<sub>N</sub>2 reactions. Most notably, π acceptors such as PF<sub>3</sub> significantly decrease the barrier to subsitution by decreasing electron density in the very electron rich transition state. Such π-backbonding represents an example of a heretofor unexplored situation in halogen bonding: the combination of both s-donation and π-backdonation in this “non-covalent” interaction.

scholarly journals Application of Halogen Bonding to Organocatalysis: A Theoretical Perspective

Molecules ◽  
2020 ◽  
Vol 25 (5) ◽  
pp. 1045 ◽  
Author(s):  
Hui Yang ◽  
Ming Wah Wong
Keyword(s):  
Crystal Engineering ◽  
Lewis Acids ◽  
Halogen Bond ◽  
Theoretical Perspective ◽  
Halogen Bonding ◽  
Catalyst Design ◽  
Methodology Development ◽  
Wide Range ◽  
Promising Area ◽  
Organocatalytic Reactions

The strong, specific, and directional halogen bond (XB) is an ideal supramolecular synthon in crystal engineering, as well as rational catalyst and drug design. These attributes attracted strong growing interest in halogen bonding in the past decade and led to a wide range of applications in materials, biological, and catalysis applications. Recently, various research groups exploited the XB mode of activation in designing halogen-based Lewis acids in effecting organic transformation, and there is continual growth in this promising area. In addition to the rapid advancements in methodology development, computational investigations are well suited for mechanistic understanding, rational XB catalyst design, and the study of intermediates that are unstable when observed experimentally. In this review, we highlight recent computational studies of XB organocatalytic reactions, which provide valuable insights into the XB mode of activation, competing reaction pathways, effects of solvent and counterions, and design of novel XB catalysts.

scholarly journals Halogen Bonding in New Dichloride-Cobalt(II) Complex with Iodo Substituted Chalcone Ligands

Crystals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 354 ◽  
Author(s):  
Lukáš Masaryk ◽  
Ján Moncol ◽  
Radovan Herchel ◽  
Ivan Nemec
Keyword(s):  
Density Functional ◽  
Halogen Bond ◽  
Halogen Bonding ◽  
Noncovalent Interaction ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray ◽  
The Density Functional Theory ◽  
Non Covalent Interactions ◽  
Covalent Interactions

The synthesis and properties of new chalcone ligand 4I-L ((2E)-1-[4-(1H-imidazol-1-yl)phenyl]-3-(4-iodophenyl)prop-2-en-1-one) and tetracoordinate Co(II) complex [Co(4I-L)2Cl2], (1a), are reported in this article. Upon recrystallization of 1a, the single crystals of [Co(4I-L)4Cl2]·2DMF·3Et2O (1b) were obtained and crystal structure was determined using X-ray diffraction. The non-covalent interactions in 1b were thoroughly analyzed and special attention was dedicated to interactions formed by the peripheral iodine substituents. The density functional theory (DFT), atoms in molecule (AIM) and noncovalent interaction (NCI) methods and electronic localization function (ELF) calculations were used to investigate halogen bond formed between the iodine functional groups and co-crystallized molecules of diethyl ether.

scholarly journals Design and Synthesis of a Chiral Halogen-Bond Donor with a Sp3-Hybridized Carbon–Iodine Moiety in a Chiral Fluorobissulfonyl Scaffold

Molecules ◽  
2020 ◽  
Vol 25 (19) ◽  
pp. 4539
Author(s):  
Hiroto Uno ◽  
Kohei Matsuzaki ◽  
Motoo Shiro ◽  
Norio Shibata
Keyword(s):  
Halogen Bond ◽  
Aldol Reaction ◽  
Asymmetric Induction ◽  
Nmr Titration ◽  
Titration Experiment ◽  
Mukaiyama Aldol Reaction ◽  
Design And Synthesis ◽  
Mukaiyama Aldol

The first example of a chiral halogen-bond donor with a sp3-hybridized carbon–iodine moiety in a fluorobissulfonyl scaffold is described. The binaphthyl backbone was designed as a chiral source and the chiral halogen-bond donor (R)-1 was synthesized from (R)-1,1′-binaphthol in 11 steps. An NMR titration experiment demonstrated that (R)-1 worked as a halogen-bond donor. The Mukaiyama aldol reaction and quinoline reduction were examined using (R)-1 as a catalyst to evaluate the asymmetric induction.

scholarly journals Experimental investigation of halogen-bond hard–soft acid–base complementarity

2017 ◽  
Vol 73 (2) ◽  
pp. 203-209 ◽  
Author(s):  
Asia Marie S. Riel ◽  
Morly J. Jessop ◽  
Daniel A. Decato ◽  
Casey J. Massena ◽  
Vinicius R. Nascimento ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Halogen Bond ◽  
Noncovalent Interaction ◽  
Computational Studies ◽  
Donor Atom ◽  
Acid Base ◽  
State Data ◽  
Lewis Bases ◽  
Soft Acid ◽  
Solution Speciation

The halogen bond (XB) is a topical noncovalent interaction of rapidly increasing importance. The XB employs a `soft' donor atom in comparison to the `hard' proton of the hydrogen bond (HB). This difference has led to the hypothesis that XBs can form more favorable interactions with `soft' bases than HBs. While computational studies have supported this suggestion, solution and solid-state data are lacking. Here, XB soft–soft complementarity is investigated with a bidentate receptor that shows similar associations with neutral carbonyls and heavy chalcogen analogs. The solution speciation and XB soft–soft complementarity is supported by four crystal structures containing neutral and anionic soft Lewis bases.

scholarly journals Catalytic Activation via π –Backbonding in Halogen Bonds?

2020 ◽  
Author(s):  
Andrew Wang ◽  
Pierre Kennepohl
Keyword(s):  
Halogen Bond ◽  
Halogen Bonding ◽  
Lewis Base ◽  
Computational Studies ◽  
Halogen Bonds ◽  
Covalent Interaction ◽  
Lewis Bases ◽  
Chemical Catalysis ◽  
Catalytic Activation

The role of halogen bonding (XB) in chemical catalysis has largely involved using XB donors as Lewis acid activators to modulate the reactivity of partner Lewis bases. We explore a more uncommon scenario, where a Lewis base modulates reactivity via a spectator halogen bond interaction. Our computational studies reveal that spectator halogen bonds may play an important role in modulating the rate of S<sub>N</sub>2 reactions. Most notably, π acceptors such as PF<sub>3</sub> significantly decrease the barrier to subsitution by decreasing electron density in the very electron rich transition state. Such π-backbonding represents an example of a heretofor unexplored situation in halogen bonding: the combination of both s-donation and π-backdonation in this “non-covalent” interaction.

Mukaiyama Aldol Reaction Catalyzed by (Benz)imidazolium-Based Halogen Bond Donors

2020 ◽  
Author(s):  
Revannath L. Sutar ◽  
Nikita Erochok ◽  
Stefan Huber
Keyword(s):  
Halogen Bond ◽  
Aldol Reaction ◽  
Mukaiyama Aldol Reaction ◽  
Mukaiyama Aldol ◽  
Background Reaction ◽  
Strong Performance ◽  
The Stability ◽  
Elemental Iodine

A series of cationic monodentate and bidentate iodo(benz)­imidazolium-based halogen bond (XB) donors were employed as catalysts in a Mukaiyama aldol reaction. While 5 mol% of a monodentate variant showed noticeable activity, a <i>syn</i>-preorganized bidentate XB donor provided a strong performance even with 0.5 mol% loading. In contrast to the very active BAr<sup>F</sup><sub>4</sub> salts, PF<sub>6</sub> or OTf salts were either inactive or showed background reaction. Repetition experiments clearly ruled out a potential hidden catalysis by elemental iodine and demonstrated the stability of our catalyst over three consecutive cycles.

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