Synthesis of n,n′‐biquinolines by a coupling reaction of bromoquinolines using organonickel(0) complexes

Abstract

Tris(triphenylphosphine)nickel(O)(A) and a zerovalent pyridine-nickel complex (B) have been used as reagents for the coupling reaction of 3-, 6-and 8-bromoquinolines: 3,3'-, 6-6'-and 8,8'-Biquinolines were obtained in quantitative yields when A was used as the coupling reagent. B gave always a mixture of the n,n'-biquinoline and substitution products. A mechanism can be outlined to explain the coupling reaction of bromoquinolines using zerovalent nickel complexes.

Friedländer Approach for the Incorporation of 6-Bromoquinoline into Novel Chelating Ligands

“…The very strong emission (φ ) 0.658) observed for 13 seems to bear out this premise. As a further test, we prepared the parent 6,6′-biquinoline (20) by the dimerization of 6-bromoquinoline 16 and found that it emitted at 352 and 372 nm with φ ) 0.100. Future work will report the coordination properties of these systems.…”

Rh(III)-Catalyzed C(8)–H Activation of Quinoline N-Oxides: Regioselective C–Br and C–N Bond Formation

“…Product 3a was successfully converted to corresponding 2-aryl-8-brominated quinoline N -oxide ( 3aa ) and 8-bromoquinoline ( 3ab ) in good yield by following the reported procedures. , C2-chlorination and C2-methoxylation , of 3a afforded corresponding products in 50 and 76% yields, respectively. In addition, 8,8′-biquinoline ( 3ae ) was synthesized from 3a in 48% yield …”

Synthesis of Biquinolines via a Pd‐Catalyzed Borylation Reaction

“…We thus set our task to develop a feasible, efficient, generalized and cost‐effective synthetic route for biquinoline scaffolds. The reported methods for N,N’‐ biquinolines are limited to 3,3’‐, 6,6’‐ and 8,8’‐biquinolines, with extended reaction time (24 h) . Although, C−H functionalization approach is also explored to afford biquinoline scaffold but its reactivity is limited till proximal position of quinoline N‐oxide directing part .…”

“…The reported methods for N,N'-biquinolines are limited to 3,3'-, 6,6'and 8,8'-biquinolines, with extended reaction time (24 h). [6,7] Although, CÀ H functionalization approach is also explored to afford biquinoline scaffold but its reactivity is limited till proximal position of quinoline N-oxide directing part. [8] So, efforts in order to broaden the scope for bi-N-heterocycles synthesis, which could offer a new generalized synthetic methodology for various bi-N-heterocycles were initiated.…”