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08 May 01:08

De Novo Synthesis of Highly Functionalized Benzimidazolones and Benzoxazolones through an Electrochemical Dehydrogenative Cyclization Cascade

by Fan Xu, Hao Long, Jinshuai Song, Hai-Chao Xu
Angewandte Chemie International Edition De Novo Synthesis of Highly Functionalized Benzimidazolones and Benzoxazolones through an Electrochemical Dehydrogenative Cyclization Cascade

It's electrifying! An electricity‐powered synthesis of highly substituted benzimidazolone and benzoxazolone derivatives is reported, in which de novo construction of the benzene and the heterocyclic ring is achieved through a dehydrogenative cyclization cascade. The electrosynthesis method proceeds with H2 evolution, thus obviating the need for oxidizing reagents and proton acceptors.


Abstract

Benzimidazolone and benzoxazolone moieties are important scaffolds in a variety of pharmaceutical molecules. These bicyclic heterocycles are usually prepared from a benzene derivative through the construction of an additional five‐membered heterocyclic ring. We report herein a method that enables the efficient synthesis of highly substituted benzimidazolone and benzoxazolone derivatives by building both the benzene and the heterocyclic rings through a dehydrogenative cyclization cascade. Readily available arylamine‐tethered 1,5‐enynes undergo a biscyclization/dehydrogenation cascade to afford functionalized benzanellated heterocycles in a single step with complete control of regioselectivity. These electricity‐powered oxidative transformations proceed with H2 evolution, thus obviating the need for transition‐metal‐based catalysts and oxidizing reagents.

08 Nov 05:17

Nickel-Catalyzed Esterification of Aliphatic Amides

by Liana Hie, Emma L. Baker, Sarah M. Anthony, Jean-Nicolas Desrosiers, Chris Senanayake, Neil K. Garg

Abstract

Recent studies have demonstrated that amides can be used in nickel-catalyzed reactions that lead to cleavage of the amide C−N bond, with formation of a C−C or C−heteroatom bond. However, the general scope of these methodologies has been restricted to amides where the carbonyl is directly attached to an arene or heteroarene. We now report the nickel-catalyzed esterification of amides derived from aliphatic carboxylic acids. The transformation requires only a slight excess of the alcohol nucleophile and is tolerant of heterocycles, substrates with epimerizable stereocenters, and sterically congested coupling partners. Moreover, a series of amide competition experiments establish selectivity principles that will aid future synthetic design. These studies overcome a critical limitation of current Ni-catalyzed amide couplings and are expected to further stimulate the use of amides as synthetic building blocks in C−N bond cleavage processes.

Thumbnail image of graphical abstract

Going aliphatic: In prior studies the nickel-catalyzed activation of aromatic amides to forge C−C or C−heteroatom bonds through cleavage on the amide C−N bond has been developed. The first nickel-catalyzed activation of amides derived from aliphatic carboxylic acids is now described, thus overcoming the key limitation associated with this class of reactions.

18 Oct 20:11

C-Functionalized, Air- and Water-Stable 9,10-Dihydro-9,10-diboraanthracenes: Efficient Blue to Red Emitting Luminophores

by Christian Reus, Sabine Weidlich, Michael Bolte, Hans-Wolfram Lerner and Matthias Wagner

TOC Graphic

Journal of the American Chemical Society
DOI: 10.1021/ja406766e
16 Aug 13:50

Design of a Photoswitchable Cadherin

by Ryan S. Ritterson, Kristopher M. Kuchenbecker, Michael Michalik and Tanja Kortemme

TOC Graphic

Journal of the American Chemical Society
DOI: 10.1021/ja404992r