Ruthenium(II)-Catalyzed C–H Bond Activation and Functionalization

The use of coordinating moieties as directing groups for the functionalization of aromatic CH bonds has become an established tool to enhance reactivity and induce regioselectivity. Nevertheless, with regard to the synthetic applicability of CH activation, there is a growing interest in transformations in which the directing group can be fully abandoned, thus allowing the direct functionalization of simple benzene derivatives. However, this approach requires the disclosure of new strategies to achieve reactivity and to control selectivity. In this review, recent advances in the emerging field of non-chelate-assisted CH activation are discussed, highlighting some of the most intriguing and inspiring examples of induction of reactivity and selectivity.

Beyond directing groups: transition-metal-catalyzed C-H activation of simple arenes.

Alkylation reactions represent an important organic transformation to form C–C bonds. In addition to conventional approaches with alkyl halides or sulfonates as alkylating agents, the use of unactivated olefins for alkylations has become attractive from both cost and sustainability viewpoints. This Review summarizes transition-metal-catalyzed alkylations of various carbon–hydrogen bonds (addition of C–H bonds across olefins) using regular olefins or 1,3-dienes up to May 2016. According to the mode of activation, the Review is divided into two sections: alkylation via C–H activation and alkylation via olefin activation.

Transition-Metal-Catalyzed C–H Alkylation Using Alkenes

Der Einsatz von koordinierenden Gruppen als dirigierende Gruppen ist eine zuverlassige Methode zur Kontrolle von Reaktivitat und Selektivitat bei der Aktivierung von Aryl-C-H-Bindungen. Im Hinblick auf die Anwendbarkeit von C-H-Aktivierungen in der Synthese besteht derzeit ein groses Interesse daran, Reaktionen zu entwickeln, in denen vollig auf dirigierende Gruppen verzichtet werden kann und somit die Funktionalisierung einfacher Benzolderivate moglich wird. Dieser Ansatz erfordert jedoch neue Strategien zur Reaktivitats- und Selektivitatskontrolle. In diesem Kurzaufsatz werden aktuelle Fortschritte in dem noch jungen Gebiet der nicht-chelatvermittelten C-H-Aktivierung diskutiert, wobei einige inspirierende Beispiele zur Reaktivitats- und Selektivitatsinduktion hervorgehoben werden.

Jeremy R. Andreatta

Papers

Transition metal catalyzed hydroarylation of olefins using unactivated substrates: Recent developments and challenges