A detailed study of the intramolecular hydroamination of N-(ortho-alkynyl)aryl-N'-substituted trifluoroacetamidines and bromodifluoroacetamidines.

The intramolecular hydroamination of N-(ortho-alkynyl)aryl-N'-substituted trifluoroacetamidines and bromodifluoroacetamidines is studied in detail. When the substituents on the alkyne fragment are aryl and alkyl groups, 5-endo-dig cyclization occurs utilizing NaAuCl(4)·2H(2)O as a catalyst, while 6-exo-dig cyclization proceeds in the presence of K(2)CO(3) as a base. Interestingly, the indole derivatives are afforded with good regioselectivity via a 5-endo-dig pathway catalyzed by Cu(OAc)(2) when ortho-ethynyl appears on the aryl substituent of the amidine. The electrophilic cyclization of the amidines also shows good regioselectivity under the I(2)/NaHCO(3) system. At the end, a facile cascade synthesis of fluorinated quinazolones is described via hydroamination/ozonolysis from the corresponding amidine.