Synthesis of chromeno[2,3- b]chromenes from 2-dimethylaminophenols and malononitrile.

5 a-Amino-5 aH,11 H-chromeno[2,3- b]chromene-11 a(12 H)-carbonitriles were synthesized from malono-nitrile and o-quinone methides, generated in situ by the thermolysis of phenolic Mannich bases in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene. It was also shown that this heterocyclic system can be obtained from 2-amino-4 H-chromene-3-carbonitriles and the aforementioned o-quinone methides. [ABSTRACT FROM AUTHOR]