Ru(II)‐Catalyzed CH Bond Activation and Alkyne Annulation Reactions

The transition metal‐catalyzed C−H activation and annulation reactions have gained significant attention over the past two decades as it is one of the most versatile transformation reactions enabling to variety of interesting complex molecular motifs with high atom and step economy. Among the transition metals exploited in this field, Ru metal is particularly important because it is less expensive and more elusive in nature. This review article sheds light on various Ru‐catalyzed C−H activation/annulation reactions, resulting in novel carbacycles, heterocycles, and spirocycles. The presence of directing groups in the aryl substrates controlling the regioselectivity, chemoselectivity, and stereoselectivity of the products is also discussed herein.