Reaction of 2-pyridyllithium with azine N-oxides. Simple and convenient method for the synthesis of 2,2′-bipyridine 1-oxide and 2,2′:6′,2″:6″2′″-tetrapyridine 1′-oxide

Abstract

In the reaction of 2-pyridyllithium with quinoline 1-oxide and isoquinoline 2-oxide a nucleophilic substitution of hydrogen occurs to form the corresponding pyridin-2-ylquinolines. A dimerization of the substrate occurs with pyridine 1-oxide, 2,2'-bipyridine 1-oxide or quinoxaline N-oxide. A similar dimerization in good yield occurs when treating azine N-oxides with tert-butyllithium and this serves as a simple and convenient method for preparing bi-and tetrapyridines.

Quaterpyridines as Scaffolds for Functional Metallosupramolecular Materials

“…H 2 O 2 or MCPBA readily converts pyridyl-N to pyridyl-NO, causing neighboring ortho positions to become vulnerable to heterocoupling reactions or substitution with chloride or bromide moieties. An example of the latter was already shown in Figure , whereas the former is seen in the consecutive coupling of pyridine 1-oxide to give 2,2′:6′,2″:6″,2‴-quaterpyridine-1-oxide 71 , a precursor of qtpy-type ligand 17 after reduction with triethylphosphite (Figure , magenta frame) . If there is no such polarizing group or if transformation into the N-oxide is impossible, simple qtpy-type ligands can be synthesized by metal-mediated dehydrogenative coupling under solvothermal conditions (Figure , green frame), , although such methods are best considered serendipitous.…”

Synthesis of quinoxaline derivatives via aromatic nucleophilic substitution of hydrogen

“…This process has been reported previously. 27 This reaction, which proceeds via deprotonation of the ring of 3 , competes with the reaction with carbanions. Indeed, the treatment of quinoxaline N -oxide with tert -BuOK in THF at −20 °C results in the formation of the dimer in a high yield.…”

Recent Progress in Non‐Catalytic C–H Functionalization of Heterocyclic N‐Oxides

“…As C‐nucleophiles, it is possible to use independently prepared organolithium [ 61–67 ] and organomagnesium [ 68–72 ] compounds.…”

“…[60] This approach can serve as an alternative to catalytic cross-coupling reactions. As C-nucleophiles, it is possible to use independently prepared organolithium [61][62][63][64][65][66][67] and organomagnesium [68][69][70][71][72] compounds.…”