Construction of Substituted 2-Aminophenols via Formal [3 + 3] Cycloaddition of Alkyl 2-Aroyl-1-chlorocyclopropanecarboxylate with in Situ Generated Enamines.

A one-pot, three-component reaction between alkyl 1-chlorocyclopropanecarboxylate, alkyne diester, and amine is developed. This cascade reaction proceeds smoothly to afford substituted 2-aminophenols in high yields. The process proceeds through a formal [3 + 3] cycloaddition between an enamine and a cyclopropene intermediate formed in situ. The substituted 2-aminophenols can be transformed into phenoxazines and benzoxazole derivatives with the treatment of PIDA.