DNA Cleavage by a Nine‐Membered Masked Enediyne, an Analogue of the Kedarcidin and C‐1027 Chromophores

A phthalate group serves as the trigger for controlling the stability of the enediyne precursor 1 . β‐Elimination of this trigger generates the corresponding enediyne and the DNA‐cleaving biradical. The highly strained nine‐membered ring in 1 , an analogue of the kedarcidin chromophore, was constructed by a transannular [2,3] Wittig rearrangement. Incubation of supercoiled DNA with 1 (1 m M ) leads to double strand cleavage without the addition of a reducing agent, which is required for other DNA cleaving systems.