Transition-metal-catalyzed direct arylation of (hetero)arenes by C-H bond cleavage

The area of transition-metal-catalyzed direct arylation through cleavage of C-H bonds has undergone rapid development in recent years, and is becoming an increasingly viable alternative to traditional cross-coupling reactions with organometallic reagents. In particular, palladium and ruthenium catalysts have been described that enable the direct arylation of (hetero)arenes with challenging coupling partners--including electrophilic aryl chlorides and tosylates as well as simple arenes in cross-dehydrogenative arylations. Furthermore, less expensive copper, iron, and nickel complexes were recently shown to be effective for economically attractive direct arylations.

Recent advances in the synthesis of indole and quinoline derivatives through cascade reactions

Indoles and quinolines are ubiquitous structural motifs in many natural products and biologically active pharmaceuticals. The pursuit of synthetic efficiency has stimulated the design and development of new synthetic strategies to construct these heterocycles. One of the most effective ways of achieving efficiency is to implement reaction cascades, enabling multiple bond-forming and bond-cleaving events to occur in a single synthetic operation, thus circumventing the waste associated with traditional stepwise synthesis. In general, cascade reactions offer the opportunity to access highly functionalized final products from simple starting materials. For all these reasons, it is not a surprise that most of the recently reported methods for the synthesis of indoles and quinolines are based on the use of cascade reactions. In this Focus Review we discuss some of the most representative and interesting recent reports on the synthesis of indoles and quinolines through cascade reactions.

Palladium-catalysed direct 3- or 4-arylation of 2,5-disubstituted pyrrole derivatives: an economically and environmentally attractive procedure

Straight to the point: The direct 3- or 4-arylation of pyrrole derivatives through C--H bond activation proceeds in moderate to good yields using Pd(OAc)(2) as catalyst. In contrast to classical coupling procedures, the preparation of an organometallic derivative is not required and the major by-products are AcOH/KBr instead of metallic salts.