Studies on Cinnamonitriles: The Reaction of Cinnamonitriles with Cyclopentanone

Abstract Cyclopentanone reacts with arylidenemalononitriles 1a–c to give dihydro‐4,6‐indenedicarbonitriles 5a–c. Similarly, the diethyl dihydro‐4,6‐indenedicarboxylate derivative 6 is formed when treating ethyl α‐cyanocinnamate (1d) with cyclopentanone. Cyclopenta[b]pyrans 5a–c are obtained from the reaction of diarylidene derivatives of cyclopentanone with malononitrile.