Coupling aromatic compounds, carbon hydrogen

In general there is a good correlation between bond distances in fused aromatic compounds and bond orders. Another experimental quantity that correlates well with the bond order of a given bond in an aromatic system is the nmr coupling constant for coupling between the hydrogens on the two carbons of the bond.74... 

Aromatic carbon—hydrogen bonds, catalzyed borylation, 9, 172 Aromatic carbonyl compounds, in samarium pinacol couplings,... 

A coupling between adjacent hydrogen atoms is also observed for naphthalenes, phenanthrenes, pyridines, quinolines (the nitrogen atom being treated as a substituted carbon atom of a benzene ring), and other aromatic compounds. 

The volume III/35D contains chenucal shifts S (in ppm) and coupling constants J (in Hz) for carbon-13 nuclei. The present subvolume III/35D, Part 2 provides data for aromatic compounds. For each nucleus the arrangement of compoimds is based on their gross formulae arranged according to Hill s system carbon comes first, hydrogen second and then other element in alphabetical order. 

On the other hand, the direct arylation of carbanionic species generated from substrates having relatively acidic hydrogens such as active methylene compounds and ketones can occur (mechanism B) [5,6]. Aryl halides are also capable of coupling directly with appropriately functionalized aromatic substrates and five-membered heteroaromatic compounds as formal carbon nucleophiles via cleavage of their unactivated C-H bonds [5,7-9]. The Fujiwra-Moritani reaction, which is the arylation of alkenes with arenes, is also useful for preparing arylalkenes without employing any halides (mechanism D) [10,11]. 

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