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Updated: Sep 19, 2025

Palladium N-Heterocyclic Carbene Complexes: Synthesis from Benzimidazolium Salts and Catalytic Activity in Carbon-carbon Bond-forming Reactions
Published on: July 30, 2017
Palladium-Catalyzed Regio- and Monoselective B(2)-H Alkylation of Zwitterionic nido-Carboranes at Room Temperature in
Ping Li1, Cheng Wen1, Xiang Li1
1School of Chemistry and Chemical Engineering, Hainan University, Haikou 570228, China.
Abstract:
The achievement of regio- and monoselective control is a fundamental challenge for the development of efficient B-H functionalization of polyhedral carboranes bearing multiple chemically similar B-H bonds. While exo-polyhedral B-H activation of zwitterionic nido-carboranes has witnessed remarkable progress, developing direct functionalization methods for the closed polyhedral B-H bonds remains a significant challenge. Herein, we report the development of a regioselective B(2)-H monoalkylation of nido-carboranes enabled by a novel pyridyl directing group containing a NH group that can form a favorable macrocyclic intramolecular H-bonding interaction with the alkyl substituent. A simple methyl substitution significantly enhances directing group efficacy, leading to unconventional B(2) selectivity. Exclusive monoselectivity was observed in the presence of three proximal B-H bonds, including a highly reactive exo-polyhedral B(11)-H site. Notably, the reaction proceeds in both water and organic solvents at room temperature.
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