Halogen Bond Catalyzed Bromocarbocyclization

Chan, Yiu-Che; Yeung, Ying‐Yeung

doi:10.1002/anie.201800261

Cited by 92 publications

(39 citation statements)

References 90 publications

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“…Equation (1) suggests that in the high density region ρ 4/3 dominates over |∇ρ| and s(ρ) decreases steadily. As |∇ρ| approaches zero at a bcp, s(ρ) goes to zero.…”

Section: Charge Density Models For Visualizing Noncovalent Interactionsmentioning

confidence: 99%

“…There is much ongoing discussion on halogen-centered noncovalent interactions and many interesting papers [1][2][3] and reviews [4][5][6][7] have appeared. Essentially, these seek to provide a fundamental understanding of their characteristic signatures [8,9], the underlying physical chemistry involved, and the way they drive packing between molecules of interest in the development of engineered crystals [10].…”

Section: Introductionmentioning

confidence: 99%

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Halogen Bonding: A Halogen-Centered Noncovalent Interaction Yet to Be Understood

2019

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In addition to the underlying basic concepts and early recognition of halogen bonding, this paper reviews the conflicting views that consistently appear in the area of noncovalent interactions and the ability of covalently bonded halogen atoms in molecules to participate in noncovalent interactions that contribute to packing in the solid-state. It may be relatively straightforward to identify Type-II halogen bonding between atoms using the conceptual framework of σ-hole theory, especially when the interaction is linear and is formed between the axial positive region (σ-hole) on the halogen in one monomer and a negative site on a second interacting monomer. A σ-hole is an electron density deficient region on the halogen atom X opposite to the R–X covalent bond, where R is the remainder part of the molecule. However, it is not trivial to do so when secondary interactions are involved as the directionality of the interaction is significantly affected. We show, by providing some specific examples, that halogen bonds do not always follow the strict Type-II topology, and the occurrence of Type-I and -III halogen-centered contacts in crystals is very difficult to predict. In many instances, Type-I halogen-centered contacts appear simultaneously with Type-II halogen bonds. We employed the Independent Gradient Model, a recently proposed electron density approach for probing strong and weak interactions in molecular domains, to show that this is a very useful tool in unraveling the chemistry of halogen-assisted noncovalent interactions, especially in the weak bonding regime. Wherever possible, we have attempted to connect some of these results with those reported previously. Though useful for studying interactions of reasonable strength, IUPAC’s proposed “less than the sum of the van der Waals radii” criterion should not always be assumed as a necessary and sufficient feature to reveal weakly bound interactions, since in many crystals the attractive interaction happens to occur between the midpoint of a bond, or the junction region, and a positive or negative site.

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“…Equation (1) suggests that in the high density region ρ 4/3 dominates over |∇ρ| and s(ρ) decreases steadily. As |∇ρ| approaches zero at a bcp, s(ρ) goes to zero.…”

Section: Charge Density Models For Visualizing Noncovalent Interactionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Halogen Bonding: A Halogen-Centered Noncovalent Interaction Yet to Be Understood

2019

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“…At the start of halogen bond catalysis, the catalysts employed were neutral XB-donors [16,20,57]. At length, it was discovered experimentally that charge-enhanced XB catalysts are more potent donors than the charge-neutral ones, as the latter often failed to give any detectable product yields in a few reported experimental attempts [19,21,23,25,58]. Despite the comparatively weaker donor strength, neutral XB catalysts have several advantages over cationic catalysts.…”

Section: Transition State and Binding Xb Complex Studiesmentioning

confidence: 99%

Application of Halogen Bonding to Organocatalysis: A Theoretical Perspective

Hui

Wong

2020

Molecules

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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.

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“…In 2018, the Yeung group demonstrated a halogen bond‐catalyzed, bromiranium ion‐induced Friedel–Crafts‐type cyclization to access bromo‐functionalized tetrahydroquinoline and chroman cores as single diastereoisomers (Scheme ) . In this transformation it is presumed that the halogen‐bond catalyst, 4‐iodo‐ N ‐methylpyridinium salt 58 , activates 1,3‐dibromo‐5‐5‐dimethylhydantoin (DBDMH) as the electrophilic brominating agent to generate a bromiranium ion intermediate from the corresponding alkenes.…”

Section: Reaction Classesmentioning

confidence: 99%

Stereoselective Haliranium, Thiiranium and Seleniranium Ion‐Triggered Friedel–Crafts‐Type Alkylations for Polyene Cyclizations

Maji

2019

Adv Synth Catal

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Ther eview is aimeda tdescribingt he advances in electrophilic "iranium" ion-triggered Friedel-Crafts-type alkylation for polyenec yclizations. Owing to the greatp otential of halo-, seleno-and sulfeno-functionalized Friedel-Crafts alkylated compounds,n umerous catalytic methodsh aveb een developed in either racemico re nantiopure forms. More importantly,t hese arene-alkylated or polyenecyclized productsc ontaining halo,s eleno ands ulfeno functionality couldb eu seful in further synthetic planning to access biologically active molecules and natural productsw ith highly complex architectures. Starting from aw ide range of classicalL ewis acids, Brønsted acids and Lewis bases through to the very recently developed halogen bondc atalysts (XB-cat.), selenonium cations as Lewis acids etc. are utilized to access these types of compounds.M orer ecently, some of the co-operative catalytic systems such as phosphite-thiourea, sulfonic acid-phosphoramidite, sulfonic acid-selenophosphoramide,s ulfonic acidanion binding thiourea, etc. catalyzing highly diastereo-and enantioselective polyene cyclizations have also been described. Thec onfigurational stability,r eactivity and selectivity of three-membered cationic

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Halogen Bond Catalyzed Bromocarbocyclization

Cited by 92 publications

References 90 publications

Halogen Bonding: A Halogen-Centered Noncovalent Interaction Yet to Be Understood

Halogen Bonding: A Halogen-Centered Noncovalent Interaction Yet to Be Understood

Application of Halogen Bonding to Organocatalysis: A Theoretical Perspective

Stereoselective Haliranium, Thiiranium and Seleniranium Ion‐Triggered Friedel–Crafts‐Type Alkylations for Polyene Cyclizations

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