Abstract

Construction of the C-C bond has been a challenge for organic chemists because of the reactivity of carbon atoms. The development of nucleophilic carbon was started with the Grignard reagent, enolate, and then ylide, however, the aromatic carbon activation was challenging till the era of organometallic chemistry. The organometallic chemistry was recognized when the Nobel Prize 2010 was given for the C-C bond forming organmetallic reaction; however, the pre functionalization of the C-H bond was an additional step with halogenated reagent, which was the limitation of this reaction. Later, the C-H activation with organometals like Pd, Ru, Cu, Rh, and other transition metal came into existence, where the directing group and metals were found to be sufficient to form the nonreactive C-C bond. In spite of several organometals, Ru acquired a special place due to the reactivity, cost and, stability. Various C-H activation reaction protocols were reported with their high regioselectivity as well as high atom economy. The C-H activation protocol involves the next level of development like SP3, SP2 ortho, meta, and para C-H activation. Here, our aim is to summarize the information regarding Ru and their ortho -regioselective reactions with the help of directing groups. The reader will benefit from the concept and the mechanism of C-H activation with the relevant examples, which have been summarized herein with the various Ru based regioselective reactions through weak and strong coordination of metal and substrate.

Keywords: C-H activation, ruthenium, regioselective C-H activation, C-C bond formation, metal based C-H activation, ortho C-H activation.

Graphical Abstract