Iron-catalyzed C(sp(2))-H and C(sp(3))-H methylations of amides and anilides.

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.

Iron-catalyzed C(sp(2))-H and C(sp(3))-H arylation by triazole assistance.

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.

Ruthenium-catalyzed alkyne annulations with substituted 1H-pyrazoles by C-H/N-H bond functionalizations.

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.

Oxidative alkenylation of aromatic esters by ruthenium-catalyzed twofold C-H bond cleavages.

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.

Versatile synthesis of isocoumarins and α-pyrones by ruthenium-catalyzed oxidative C-H/O-H bond cleavages.

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.