2‐(3‐Pyrrolin‐1‐yl)‐1,4‐naphthoquinones: Photoactivated Alkylating Agents

Abstract The preparation of 2‐(3‐pyrrolin‐1‐yl)‐1,4‐naphthoquinones and a study of their use as photoactivated alkylating agents is reported. The title compounds were easily synthesized by conjugate addition of the corresponding 3‐pyrrolines to various naphthoquinones. Upon exposure to ambient room light, the compounds undergo an internal redox reaction to form 2‐(pyrrol‐1‐yl)‐1,4‐hydroquinones, which are activated for nucleophilic addition by an S N 1 azafulvene mechanism. Control experiments demonstrated that the redox reaction is triggered by light and that the nucleophilic addition does not proceed before this activation occurs.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)