Synthesis of New Furo[3,4‐ b ]quinolin‐1(3 H )‐one Scaffolds Derived from γ ‐Lactone‐Fused Quinolin‐4(1 H )‐ones

In the context of our aim of discovering new antitumor drugs among synthetic γ ‐lactone‐ and γ ‐lactam‐fused 1‐methylquinolin‐4(1 H )‐ones, we developed a rapid access to 5‐methyl‐1,3‐dioxolo[4,5‐ g ]furo[3,4‐ b ]quinoline‐8,9(5 H ,6 H )‐dione ( 9 ) exploiting the γ ‐lactone‐fused chloroquinoline 10 previously synthesized in our laboratory ( Scheme 1 ). We also elaborated efficient synthetic methods allowing for a rapid access to two nonclassical bioisosteres of 9 , i.e. , a deoxy and a carba analogue. The deoxy analogue 11 was prepared in two steps from the γ ‐lactone‐fused quinoline 13 which was also the synthetic precursor of 10 ( Scheme 1 ). The carba analogue 6,9‐dihydro‐5‐methyl‐9‐methylene‐1,3‐dioxolo[4,5‐ g ]furo[3,4‐ b ]quinolin‐8(5 H )‐one ( 12 ) was easily prepared by HCl elimination from the 9‐(chloromethyl)dioxolofuroquinoline 15 , which was obtained via a three‐component one‐pot reaction from N ‐methyl‐3,4‐(methylenedioxy)aniline (= N ‐methyl‐1,3‐benzodioxol‐5‐amine; 16 ), commercially available chloroacetaldehyde, and tetronic acid ( 17 ) ( Scheme 2 ).