Palladium-catalyzed C-H activation/C-C cross-coupling reactions typically require stoichiometric chemical oxidants and exogenous ligands. However, there are significant disadvantages associated with the use of traditional stoichiometric oxidants. To overcome these issues, we have developed an electrochemical strategy to achieve methylation and acylation.
An electrochemical asymmetric coupling
of secondary acyclic amines
with ketones via a Shono-type oxidation has been described, affording
the corresponding amino acid derivatives with good to excellent diastereoselectivity
and enantioselectivity. The addition of an N-oxyl
radical as a redox mediator could selectively oxidize the substrate
rather than the product, although their oxidation potential difference
is subtle (about 13 mV). This electrochemical transformation proceeds
in the absence of stoichiometric additives, including metals, oxidants,
and electrolytes, which gives it good functional group compatibility.
Mechanistic studies suggest that proton-mediated racemization of the
product is prevented by the reduction of protons at the cathode.
We have developed a Ni-catalyzed enantioselective hydroarylation of styrenes with arylboronic acids using MeOH as the hydrogen source, providing an efficient method to access 1,1-diarylalkanes, which are essential structural units in many biologically active compounds. In addition, Ni-catalyzed enantioselective hydrovinylation of styrenes with vinylboronic acids is also realized with good yields and enantioselectivities. The synthetic utility was demonstrated by the efficient synthesis of (R)-(−)-ibuprofen.
Palladium-catalyzed regioselective electrocarboxylation of homostyrenyl acetates with CO2 has been successfully developed, providing α-aryl carboxylic acids with good selectivity and yield.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.