Annulation electrophilic nitrogen

Imidazole ring annulation according to variant Alg can be a result of the nucleophilic attack of the nitrogen atom in the 1- or 4-position of quinoxaline at the electrophilic carbon atom of the C-N-C moiety of the substituent at the C(2) or C(3) atom. Such substituents are acylaminomethyl, isocyanatomethyl, benzylaminomethyl, etc. 

The alkylation of pyridyl alcohols by alkyl lithium reagents proceeds regiospecifically to give products such as (122) after deprotonation of the hydroxyl function interaction of the metal cation with nitrogen is thought to enhance the electrophilicity at the 6-position. It has been shown that complexation of unsaturated alcohols, such as propar-gyl alcohols, with ruthenium allows their reaction with pyrroles and indole and may lead to alkylated, (123), or propargylated or annulated products. A zinc(II)-thiourea... 

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