Synthesis of Acridines and Persubstituted Phenols from Cyclobutenones and Active Methylene Ketones

A new benzannulation strategy that proceeds via a regiospecific
[4 + 2] cycloaddition of readily available cyclobutenones and active
methylene ketones has been developed. On the basis of this strategy,
persubstituted phenols/anilines with up to six different functional
groups on the benzene ring were synthesized in a single step. In addition,
a series of acridine derivatives were prepared in excellent yield
from persubstituted phenols/anilines.