Related Experiment Video
Updated: Apr 16, 2026

Palladium N-Heterocyclic Carbene Complexes: Synthesis from Benzimidazolium Salts and Catalytic Activity in Carbon-carbon Bond-forming Reactions
Published on: July 30, 2017
Synthesis of the first heteroaryl-substituted boryl complexes: strong stabilizing effects of boron-aryl π-conjugation
Holger Braunschweig1, Rian D Dewhurst1, Thomas Kramer1
1Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
Abstract:
The first examples of heteroarylboryl complexes were prepared and have been found to be unreactive toward a range of strong reductants, strong Lewis bases, and halide-abstraction reagents. The inertness of the complexes is attributed to strong π-conjugation between the π-basic heteroaryl groups and the π-acidic boron atom. This hypothesis is supported by comparison of the structural and spectroscopic properties of the heteroarylboryl complexes with analogous previously reported homoarylboryl complexes, with the former showing greater coplanarity of the aryl ring with the boron atom and much less facile reactivity.
More Related Videos
Related Concept Videos
Synthesis of α-Substituted Carbonyl Compounds: The Stork Enamine Reaction
Nucleophilic Aromatic Substitution: Elimination–Addition
Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
Regioselectivity and Stereochemistry of Hydroboration
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn...
Nucleophilic Aromatic Substitution of Aryldiazonium Salts: Aromatic SN1
In the Sandmeyer reaction, for example, the diazonio group is replaced by a chloro, bromo,...
Nucleophilic Aromatic Substitution: Addition–Elimination (SNAr)
The reaction begins with an attack of the nucleophile on the carbon that holds the leaving group. This results in the delocalization of the π electrons over the ring carbons. The resonance interaction between...

