Why can the Diels–Alder reaction of 9,10-diphenylanthracene with 4-phenyl-1,2,4-triazoline-3.5-dione pass by an abnormal way?

Abstract

9,10-Diphenylanthracene reacts with dienophile by 1,4-positions rather than 9,10-ones of trivial anthracenes, that has been justified with estimation of kinetic and thermodynamic parameters of the process.