Perhydrofuro[3,2-c]-, perhydropyrano[3,2-c]-, and 4-ethoxy-2-(5-R-furan-2-yl)tetrahydroquinolines. Synthesis and transformations

Partly hydrogenated 2-[5-methyl(bromo, nitro)furan-2-yl]-substituted furo[3,2-c]quinolines, pyrano-[3,2-c]quinolines, and 4-ethoxyquinolines were synthesized by the imino Diels-Alder (Povarov) reaction. Cycloadditions of these compounds with maleic, citraconic, and dibromomaleic anhydrides, as well as with acryloyl, methacryloyl, and cinnamoyl chlorides led to the formation of substituted epoxyisoindolo[2,1-a]-quinolines and -quinolinecarboxylic acids. Oxidation of the double C=C bond in the adducts, esterification of the carboxy group, and aromatization of the 7-oxabicycloheptene fragment were accomplished.