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Functionalization of the Imidazole Backbone by Means of a Tailored and Optimized Oxidative Heck Cross‐Coupling
Author(s) -
Cirillo Davide,
Angelucci Francesco,
Bjørsvik HansRené
Publication year - 2020
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.202000909
Subject(s) - chemistry , imidazole , heck reaction , combinatorial chemistry , reactivity (psychology) , surface modification , boronic acid , coupling (piping) , organic chemistry , polymer chemistry , palladium , catalysis , medicine , mechanical engineering , alternative medicine , pathology , engineering
A general and selective Pd‐catalyzed cross‐coupling of aromatic boronic acids with vinyl‐imidazoles is disclosed. Unlike most cross‐coupling reactions, this method operates well in absence of bases avoiding the formation of by‐products. The reactivity is highly enhanced by the presence of nitrogen‐based ligands, in particular bathocuproine. The method involves MnO 2 as oxidant for the oxidation Pd (0)→Pd (II), a much weaker oxidant than previously reported in the literature. This allows for the use of reactants that possess a multitude of functional groups. A scope and limitation study involving a series of 24 boronic acids, whereof 18 afforded TMs in yields in the range 41–95%. The disclosed method constitutes the first general method for the oxidative Heck cross‐coupling on the imidazole scaffold, which moreover operates with a selection of other heterocycles.