Photoamidation of N-Acetyl-2-chlorotyrosine Methyl Ester and 3-Chlorophenol

摘要

Aryl halides are stable in nucleophilic displacement reactions. 4-Chlorophenols undergo a variety of photochemical reactions to yield a plethora of products, while 3-chlorophenol undergoes photohydrolysis in water to form resorcinol.1 Since the excited state of phenols is more energetic than that of the corresponding phenoxides, excited phenols are known to ionize to excited phenoxide. On the basis of our experience in the photochemistry of 4-haloindoles and the charge distributions of the L_b excited state of benzene, the powerful electron-releasing excited phenoxide ion will delocalize a substantial portion of its charge to the meta-position. Localization of charge at the position bearing the halogen substituent may lead to its activation and subsequent displacement (see also Scheme 1).