Efficient synthesis of decahydroacridine-1,8-diones and polyhydroquinolines using the step-wise method

Various symmetrical and unsymmetrical decahydroacridine-1,8-dione and polyhydroquinoline derivatives were synthesized via two-step cyclocondensation reactions. The advantages of this step-wise addition of reactants in comparison with other one-pot reactions are avoiding the formation of 2 or 3 undesired by-products, therefore allowing cleaner work up of reaction. The important factor of this effective cyclocondensation method is that the prepared β -enaminone component was added dropwise to the solution, in which the Knoevenagel condensation product is slowly being formed by reaction of aldehyde molecule and 1,3-dicarbonyl compounds. The results of the proposed step-wise method are compared and discussed with those obtained in the one-pot reactions.