Some Reactions with Indane‐1,3‐dione: A Facile Synthesis of Pentacycline Heterocyclic Analogues

Indane‐1,3‐dione 1 reacts with salicylaldehyde 5 and malononitrile 3 to afford 6‐amino‐7‐imino‐7H‐indeno‐2′,1′:5,6]‐pyrano‐3,4 ‐ c]‐chromene 6 , which could be transformed into the corresponding 7‐oxo derivative 7 . 2‐(3‐Oxoindan‐1‐ylidene)‐malononitrile 10 couples with the diazonium salts 8 , 14 , and 15 to afford after cyclization the indeno‐2,1‐c]‐pyridazine 13 and the indeno‐2′,1′:3,4]‐pyridazino‐1,6‐a]‐quinazoline derivatives 20 and 21 , respectively.