Synthesis of New Dipyrido‐Annulated N‐Heterocyclic Carbenes with Aryl Substituents

Abstract

4,8-Aryl-substituted 2,10-di-tert-butyldipyrido[1,2-c;2Ј,1Јe]-imidazolium salts were synthesized from a newly prepared dibromoprecursor by use of Suzuki-Miyaura coupling. The corresponding carbenes were generated from the imidazolium salts by deprotonation. ARTICLE Dedicated Clusteradditional π interactions to the coordinated central metal atom.

Synthesis and Isolation of an Anionic Bis(dipyrido-annulated) N-Heterocyclic Carbene CCC-Pincer Iridium(III) Complex by Facile C–H Bond Activation

“…and Kunz et al − Both theoretical and experimental studies have shown that its aromatic dipyrido moieties contribute to empty p orbitals of the carbene carbon, resulting in a higher π-donating ability in comparison to Arduengo-type NHCs . Previously, we have successfully introduced thio, phosphinyl, − and aryl substituents to the dpa NHC backbone. The aryl-substituted dpa Ar2 NHCs were in situ generated by deprotonation of the respective imidazolium salt and characterized by complexation to a gold­(I) center (Scheme ).…”

“…The aryl-substituted dpa Ar2 NHCs were in situ generated by deprotonation of the respective imidazolium salt and characterized by complexation to a gold­(I) center (Scheme ). The percent buried volume ( V bur ), calculated by using the SambVca 2.1 server, based on the solid-state structure of our (dpa Ar2 NHC)­AuI complex is 67.2%, much larger than those found for typical aryl-substituted NHCs such as IMes and I i Pr [ca. 35–45%; I i Pr = 1,3-bis­(2,6-diisopropylphenyl)­imidazole-2-ylidene].…”

Oxidative Cyclization of 4‐(2‐Mercaptophenyl)‐Substituted 4H‐1,2,4‐Triazolium Species to Tricyclic Benzothiazolium Salts

“…A similar method was recently applied in preparation of fused azoles‐thiazolines from alkylthiocyanato‐functionalized azolium precursors [50] . However, 2‐alkylthioimidazolium salts are generally prepared by reacting the imidazolium precursor with S 8 to give the thioimidazolium species which subsequently is alkylated [51–54] . The same alkylation approach has been utilized in preparation of 3‐methylthio‐substituted 1,2,4‐triazolium salts [55,56] …”

“…[50] However, 2alkylthioimidazolium salts are generally prepared by reacting the imidazolium precursor with S 8 to give the thioimidazolium species which subsequently is alkylated. [51][52][53][54] The same alkylation approach has been utilized in preparation of 3-methylthiosubstituted 1,2,4-triazolium salts. [55,56]…”