Chronic Actinic Dermatitis to Sesquiterpene Lactones: [2+2] Photoreaction Toward Thymidine of (+) and (−) α-Methylene-Hexahydrobenzofuranone with a cis Ring Junction

• Published in: Photochemistry and photobiology Vol. 86; no. 3; pp. 545 - 552
• Main Authors: Fuchs, Sébastien, Berl, Valérie, Lepoittevin, Jean-Pierre
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-05-2010
• Subjects: 4-Butyrolactone - analogs & derivatives; 4-Butyrolactone - chemistry; Dermatitis, Allergic Contact - etiology; Humans; Lactones - chemistry; Magnetic Resonance Spectroscopy; Photosensitivity Disorders - chemically induced; Photosensitivity Disorders - etiology; Sesquiterpenes - chemistry; Sesquiterpenes - radiation effects; Thymidine - chemistry; Ultraviolet Rays - adverse effects
• ISSN: 0031-8655; 1751-1097
• DOI: 10.1111/j.1751-1097.2009.00691.x

(+) and (−) α‐methylene‐hexahydrobenzofuranone derivatives with a stereochemically pure cis ring junction were used as models of sesquiterpene lactones to study their photoreactivity toward thymidine. After 313 nm irradiation of a deoxygenated acetone solution of lactone models and thymidine, six [2+2] photoadducts were isolated for each enantiomer and fully characterized by a combination of NMR experiments. A common syn regioselectivity and exo stereoselectivity were observed for photoadducts. This high photoreactivity of α‐methylene‐γ‐butyrolactone ring toward thymidine could be an explanation of the progressive evolution of allergic contact dermatitis toward chronic actinic dermatitis.