III International Conference

PP-II-80refluxing in glacial acetic acid, so this reaction proceeds via cationic intermediate. Nitrogencontainingα-heterylamines (α-aminopyridine, α-aminothiazole etc.) reacts in absence ofcatalyst which may be explained by forming of cyclic intermediate 4.The reaction with o-phenylenediamine in presence of HCl yields benzimidazoline's spiroderivatives5 meanwhile products of this reaction in glacial acetic acid are condensedquinoxalines 6. Nucleophiles such as hydrazides and thiosemicarbazide react withoutcleavage of pyrrole's ring even in presence of acids. This fact probably may be explained byother molecule's orientation and other energy of activation consequently.310