REACTIVITY OF BENZYNE TOWARD ANTHRACENE SYSTEMS

Benzyne reacts with anthracenes to form Diels-Alder adducts with both the center and end rings of anthracene systems. The nature and position of the substituents markedly influence the relative amounts of centerand end-ring adducts formed; the electrophilic nature of benzyne and its steric requirements have been elucidated. The relative reactivities of a number of substituted anthracenes toward benzyne have been measured by a series of competition experiments. These relative reactivities generally parallel those of anthracenes toward maleic anhydride; however, some significant exceptions have been noted. Calculations of the partial relative rate factors for benzyne addition to the center and end rings of substituted anthracenes can be made from the relative reactivity and center- to end-ring adduct ratio data. In general, substituents in one ring do not affect the reactivity of the other ring toward benzyne, but 9,10-diphenylanthracene represents a noteworthy exception. © 1969, American Chemical Society. All rights reserved.