Several new chromeno[2,3-b]indole tetracycles were synthesized by the reaction of 2'-hydroxyacetophenones or 2'-hydroxypropiophenones and salicylaldehyde derivates. Under the harsh reaction conditions, the initially formed Knoevenagel adducts lost water, giving rise to the formation of ring closed tetracyclic products.
Several new chromeno[2,3-b]indole tetracycles were synthesized by the reaction of 2'-hydroxyacetophenones or 2'-hydroxypropiophenones and salicylaldehyde derivates. Under the harsh reaction conditions, the initially formed Knoevenagel adducts lost water, giving rise to the formation of ring closed tetracyclic products.