A diastereoselective synthesis of tetrahydro- and dihydro-pyrido[2,3-c]coumarin derivatives via a one-pot three-component Povarov reaction catalyzed by bismuth(III) chloride.

A diastereoselective synthesis of tetrahydro- and dihydro-pyrido[2,3-c]coumarin derivatives has been achieved via a one-pot three-component aza-Diels-Alder reaction of aromatic aldehydes, 3-aminocoumarin and dienophiles catalyzed by BiCl3. NOE studies proved that exo-isomers were obtained in all cases with high selectivity. The reaction proceeded at room temperature providing good yields of products as well as applicability on a wide range of substrates. Among all the synthesized derivatives, compounds 4i and 4k showed promising DPPH radical scavenging activity as compared to other tested derivatives.