An efficient route for the construction of cyclopenta[b]quinoline derivatives via intramolecular cyclopropanation

A one-pot process to introduce diazoacetoacetate functionality into quinoline was identified with excellent yield and regioselectivity. An intramolecular cyclopropanation of the resulting adducts gave tetracyclic cyclopenta[b]quinoline derivatives in nearly quantitative yields. A synthetic utility of the tetracyclic derivatives was examined by a simple ring opening reaction to afford cyclopenta[b]quinoline in a good yield.