Dihydrothiophenes as precursors to fused quinolines, quinolones and coumarins via o-quinodimethane intermediates

Article abstract of DOI:10.1016/0040-4020(95)01099-8

3-Methoxycarbonyl-4-keto-2,5-dihydrothiophene is a convenient starting point for synthesis of a range of 3,4- and 2,3-quinoline and quinolone and coumarin fused dihydrothiophene dioxides. With the exception of the 2,3-quinoline derivatives these all lose sulfur dioxide on thermolysis to give the corresponding o-quinodimethanes which can be intercepted in Diels-Alder reactions.