Diethyl benzylidenemalonate is used as a pharmaceutical intermediate. It is also involved in the Conjugate addition of cyanide ion to arylidenemalonic esters provides a useful route to arylsuccinic acids.
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Conjugate addition of cyanide ion to arylidenemalonic esters provides a useful route to arylsuccinic acids: Org. Synth. Coll., 4, 804 (1963):