A new approach to linear tetracycles via Michael reactions of quinizarinquinone with O-silylated ketene acetals
Abstract
The Michael-type reaction of quinizarinquinone and 1-ethoxy-1-(trimethylsiloxy)buta-1,3-diene followed by Lewis acid-catalysed [1,5] sigmatropic rearrangement and Friedel–Crafts cyclisation provides a new route to variously functionalized tetracycles.