Gimenez-Arnau E, Mabic S, Lepoittevin J P
Laboratoire de Dermatochimie associé au CNRS, Université Louis Pasteur, CHU, Strasbourg, France.
Chem Res Toxicol. 1995 Jan-Feb;8(1):22-6. doi: 10.1021/tx00043a002.
Two alpha-methylene-gamma-butyrolactone--thymine heterodimers 6 and 7 with 5 and 10 carbon alkyl chains, respectively, were prepared to study the photoreactivity of lactone rings toward thymine and the influence of spacer length on photoadduct geometry. Deoxygenated solutions (10(-3) M) of heterodimers 6 and 7 were irradiated at 365 nm in acetone. Irradiation of compound 6 (5 carbons alkyl chain) gave a single photoadduct 8 (70% yield), while irradiation of compound 7 (10 carbons alkyl chain) gave two photoadducts 9a and 9b in a 3/2 ratio (95% yield). Compound 8 was identified as a cis-syn-endo intramolecular [2 + 2] photoadduct involving the 5",6" double bond of the thymine moiety and the 3,6 exomethylenic group of the lactone. Compound 9a was identified as a cis-syn-exo intramolecular [2 + 2] photoadduct involving the 5",6" double bond of the thymine moiety and the 3,6 exomethylenic group of the lactone, and compound 9b as the corresponding cis-syn-endo intramolecular [2 + 2] photoadduct.
制备了分别带有5碳和10碳烷基链的两个α-亚甲基-γ-丁内酯-胸腺嘧啶异二聚体6和7，以研究内酯环对胸腺嘧啶的光反应活性以及间隔长度对光加合物几何结构的影响。在丙酮中，将异二聚体6和7的脱氧溶液（10⁻³ M）在365 nm波长下进行照射。照射化合物6（5碳烷基链）得到单一的光加合物8（产率70%），而照射化合物7（10碳烷基链）得到比例为3/2的两种光加合物9a和9b（产率95%）。化合物8被鉴定为一种顺式-顺式-内型分子内[2 + 2]光加合物，涉及胸腺嘧啶部分的5'',6''双键和内酯的3,6-亚甲基外基团。化合物9a被鉴定为一种顺式-顺式-外型分子内[2 + 2]光加合物，涉及胸腺嘧啶部分的5'',6''双键和内酯的3,6-亚甲基外基团，化合物9b则为相应的顺式-顺式-内型分子内[2 + 2]光加合物。
