meta‐C−H Bromination on Purine Bases by Heterogeneous Ruthenium Catalysis

Abstract

Methods for positionally selective remote C-H functionalizations are in high demand. Herein, we disclose the first heterogeneous ruthenium catalyst for meta-selective C-H functionalizations, which enabled remote halogenations with excellent site selectivity and ample scope. The versatile heterogeneous Ru@SiO catalyst was broadly applicable and could be easily recovered and reused, which set the stage for the direct fluorescent labeling of purines. In contrast to palladium, rhodium, iridium, or cobalt complexes, solely the ruthenium catalysis manifold provided access to meta-halogenated purine derivatives, illustrating the unique power of ruthenium C-H activation catalysis.

Visible‐Light‐Enabled Ruthenium‐Catalyzed meta‐C−H Alkylation at Room Temperature

“…[1] Thus far, chelation assistance by directing groups has been identified as av ersatile tool for site-selective CÀHmetalations. [9][10][11][12][13] Despite indisputable progress,t he s-activation approach is limited to elevated reaction temperatures,w hich resulted in signifi-cantly reduced yields and low functional group tolerance. [3] Exploiting the substratesi nherent substitution pattern has proven useful, but this approach still largely suffers from limited substrate scope.…”

“…As au niquely versatile alternative, meta-C À Hf unctionalizations through arene s-activation [8] were realized by chelation-assisted ortho-cycloruthenation. [9][10][11][12][13] Despite indisputable progress,t he s-activation approach is limited to elevated reaction temperatures,w hich resulted in signifi-cantly reduced yields and low functional group tolerance. Conversely,r oom-temperature metal-catalyzed meta-CÀH functionalization has thus far unfortunately proven elusive.…”

Direct oxidative C(sp3)─H/C(sp2)─H coupling reaction using recyclable Sr‐doped LaCoO3 perovskite catalyst

“…Uses of metal oxides in organic synthesis are extensively emerging. On introduction of active metals into the framework of oxide supports using impregnating methods, catalytic activity and thermal stability of transition metals are improved . Many methods that allow for the synthesis of heterocycles from metal oxide‐catalyzed, direct C─H functionalization are known .…”

“…On introduction of active metals into the framework of oxide supports using impregnating methods, catalytic activity and thermal stability of transition metals are improved. [36][37][38] Many methods that allow for the synthesis of heterocycles from metal oxidecatalyzed, direct C─H functionalization are known. [39,40] Mixtures of metal oxides are also calcined to feature synergistic effects, thus improving efficiency.…”

Sichtbares Licht ermöglicht Ruthenium‐katalysierte meta‐C‐H‐Alkylierung bei Raumtemperatur

“…Eine vielversprechende Alternative hierzu bieten meta-C-H-Funktionalisierungen auf Basis der s-Aktivierung [8] mittels Chelat-vermittelter Cycloruthenierung. [9][10][11][12][13] Die dafüre rforderlichen hçheren Reaktionstemperaturen verringern jedoch die Ausbeute und die Toleranz fürf unktionelle Gruppen. Eine bei Raumtemperatur ablaufende meta-selektive C-H-Funktionalisierung war bisher nicht bekannt.…”