Modular 1,2,3-triazoles enabled iron-catalyzed CH arylations with broad scope. The novel triazole-based bidentate auxiliary is easily accessible in a highly modular fashion and allowed for user-friendly iron-catalyzed C(sp(2) )H functionalizations of arenes and alkenes with excellent chemo- and diastereoselectivities. The versatile iron catalyst also proved applicable for challenging C(sp(3) )H functionalizations, and proceeds by an organometallic mode of action. The triazole-assisted CH activation strategy occurred under remarkably mild reaction conditions, and the auxiliary was easily removed in a traceless fashion. Intriguingly, the triazole group proved superior to previously used auxiliaries.

An inexpensive cationic ruthenium(II) catalyst enabled the expedient synthesis of isocoumarins through oxidative annulations of alkynes by benzoic acids. This C-H/O-H bond functionalization process also proved applicable to the preparation of α-pyrones and was shown to proceed by rate-limiting C-H bond ruthenation.

The so-called magic methyl effect significantly boosts the bioactivities and physical properties of pharmacologically active drugs. Direct introduction of the methyl group by CH activation was accomplished with a versatile iron catalyst, which enabled the CH methylation of (hetero)benzamides, anilides, alkenes, and even alkanes by triazole assistance in a chemo-, site- and diastereo-selective fashion.

Cationic ruthenium(II) complexes enabled catalytic twofold C-H bond functionalizations with weakly coordinating aromatic esters in a highly chemo-, site- and diastereo-selective as well as site selective fashion. The oxidative Fujiwara-Moritani-type alkenylation provided step-economical access to diversely substituted styrenes and proved viable in an aerobic manner. Mechanistic studies were indicative of a reversible acetate-assisted cycloruthenation step.

Cationic ruthenium(II) complexes allowed for highly efficient oxidative annulations of aryl- and alkyl-substituted alkynes by 5-aryl-1H-pyrazoles. The C-H/N-H bond functionalization strategy furthermore proved applicable to the high-yielding activation of heteroaryl as well as alkenyl C-H bonds.