Imino Diels-Alder reaction: Application to the synthesis of diverse cyclopenta[c]quinoline derivatives

Several unreported tetrahydrocyclopenta[c]quinoline derivatives have been prepared employing an imino Diels-Alder cycloaddition as the key ring forming step. The tetrahydroquinoline 10 can be directly oxidized into the cyanoamine 15 which upon treatment with LDA and propyl bromide is easily converted into the propyl derivative. On direct treatment with NaBH4 in methanol the reductive decyanation occurred, leading stereospecifically to 17.