Fleming Steven A, Parent Alexander A, Parent Ephraim E, Pincock James A, Renault Lise
Department of Chemistry & Biochemistry, Brigham Young University, Provo, UT 84602, USA.
J Org Chem. 2007 Dec 7;72(25):9464-70. doi: 10.1021/jo7014664. Epub 2007 Nov 13.
The photochemistry of substituted cinnamyloxy silanes has been examined in both cyclohexane and acetonitrile solvents. Alkene isomerization occurs in addition to cycloaddition. Fluorescence quantum yields and excited singlet state lifetimes have been determined for each compound. We have used the information in order to better understand the regio- and stereoselectivity of photocycloaddition between silyl-tethered cinnamyl groups. This study allows us to conclude that the 2 + 2 photocycloaddition between alkenes is not a Woodward-Hoffmann orbital symmetry controlled event. The most consistent explanation for the excellent regio- and stereoselectivity is that the photocycloaddition is conformationally controlled.
在环己烷和乙腈两种溶剂中研究了取代肉桂氧基硅烷的光化学性质。除环加成反应外，还发生烯烃异构化。已测定了每种化合物的荧光量子产率和激发单重态寿命。我们利用这些信息来更好地理解硅烷基连接的肉桂基之间光环加成反应的区域选择性和立体选择性。这项研究使我们得出结论，烯烃之间的2 + 2光环加成反应不是伍德沃德 - 霍夫曼轨道对称控制的过程。对出色的区域选择性和立体选择性最一致的解释是光环加成反应受构象控制。
