groups in ortho‐ and ortho′‐positions was investigated. Both systems underwent cyclization via tert‐amino effect. Thus, 2‐(2‐[2‐(sec‐amino)benzyl]‐N‐methylamino}benzylidene)malononitriles gave tetrahydroquinolines, whereas a 2‐[2‐(sec‐amino)phenoxy]benzylidenemalononitrile isomerized to dibenzoxazonine derivative. The ringclosure reaction was studied by differential scanning calorimetry measurements. Copyright