Heteroarylation reactions

Pyridines and their N- oxides undergo attack by enamines under acylating conditions (Scheme 168), and the results for reactions of N- oxides have been surveyed (B-71MI20500). A modification of this heteroarylation reaction has been employed in the first step of a new synthesis of the antitumor alkaloid olivacine (241 Scheme 169) (81CC44). Electron-withdrawing groups attached at C-4 in the pyridine nucleus appear to facilitate this reaction. 

Pyrrole derivatives were used as aromatic partners in photochemical heteroarylation reactions with a number of halogen-containing compounds, for example, the quinone 593 reacts with iV-methylpyrtole to give the corresponding pyrrolyl derivative 594 (Equation 141) <1997J(P1)2369>. This reaction occurs via a charge transfer complex in the ground state. 

Cross-coupling reactions of thiophenes by C-H functionalization have been extensively reviewed in the year 2014 (14ASC17). One important feature is a discussion of recent progress made in direct arylation and heteroarylation reactions involving thiophenes and other five-membered heterocycles containing one heteroatom. 

Rossi, R. Beilina, E Lessi, M. Manzini, C. Cross-coupling of heteroarenes by C-H functionalization recent progress towards direct arylation and heteroarylation reactions involving heteroarenes containing one heteroatom. Adv. Synth. Catal. 2014, 356, 17-117. 

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