Synthesis of 5-Amino-1,10b-dihydro-2H-chromeno[3,4-c]pyridine-2,4(3H)-diones from Coumarins and Cyanoacetamides under Basic Conditions

The reaction of various coumarins with cyanoacetamide derivatives under basic conditions (sodium ethoxide, piperidine or 2,2,6,6-tetramethylpiperidine), proceeds via an interesting process which involves skeletal rearrangement of the coumarin, a Michael addition and two cyclizations to afford 5-amino-1,10b-dihydro-2H-chromeno[3,4-c]pyridine-2,4(3H)-diones. The same reaction in the presence of N,N'-ethane-1,2-diylbis(2-cyanoacetamide) gives the corresponding mono and bis 5-amino-1,10b-dihydro-2H-chromeno[3,4-c]pyridine-2,4(3H)-diones.