Cascade reaction of alkynols with 1-(2-aminophenyl)prop-2-ynols to form a fused 5,5,6-tricyclic system: formation of four bonds in a single reaction.

A novel cascade reaction of internal alkynols with 1-(2-aminophenyl)prop-2-ynols has been developed to form a new N,O-containing fused 5,5,6-tricyclic skeleton. Mechanistic studies indicate that this reaction proceeds via alkynol cycloisomerization, intermolecular substitution with 1-(2-aminophenyl)prop-2-ynols, and intermolecular addition with alkynols and consequent cyclizations. In this way, two C-C bonds, one C-O bond and one C-N bond form to give a tricyclic skeleton in a single reaction.