An alternate approach to quinoline architecture via Baylis-Hillman chemistry: SnCl2-mediated tandem reaction toward synthesis of 4-(substituted vinyl)-quinolines

An alternate approach to densely substituted quinolines from the products of S_N2 nucleophilic substitution reaction between the acetyl derivatives of the Baylis-Hillman adducts obtained from 2-nitrobenzaldehydes and the carbonyl group containing carbon nucleophiles is described. Treatment of these compounds with SnCl₂, triggers a tandem reaction wherein reduction of the nitro group is followed by a remarkably regioselective intramolecular cyclization and subsequent dehydrogenation to afford 4-(substituted vinyl)-quinolines.