Photooxygenation of allylic alcohols: kinetic comparison of unfunctionalized alkenes with prenol-type allylic alcohols, ethers and acetates
Photooxygenation of allylic alcohols: kinetic comparison of unfunctionalized alkenes with prenol-type allylic alcohols, ethers and acetates
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DOI：
10.1039/b302255b
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发表时间：
2003-01-01
影响因子：
3.1
通讯作者：
El-Idreesy, TT
中科院分区：
文献类型：
--
作者：
Griesbeck, AG;Adam, W;El-Idreesy, TT
未官能化烯烃 1 - 4、烯丙醇 5 - 7 和 9、烯丙乙酸酯 8 和 11 以及烯丙醚 10 对氧的第一激发单线态 [ O-1(2) ((1)Delta(g))] 的化学和物理猝灭动力学对反应性显示出较小的溶剂极性影响。单线态氧烯反应的区域选择性对于未官能化的烯烃以及异戊烯醇型底物而言与溶剂无关，后者显示出对非对映选择性的显着溶剂影响。仅在烯丙醇 5 和 6 中检测到显着的物理猝灭。这些结果根据单线态氧和烯丙基羟基之间的相互作用进行解释，烯丙应变在构象上促进了烯丙基应变，从而导致化学活化或物理猝灭。氘代甲醇与非氘代甲醇中底物 9 的结果与烯丙醇和 O-1(2) 之间的氢键一致，这决定了烯与手性烯丙醇反应的非对映选择性。
The kinetics of the chemical and physical quenching of the first excited singlet state of oxygen [ O-1(2) ((1)Delta(g))] by unfunctionalized alkenes 1 - 4, allylic alcohols 5 - 7 and 9, allylic acetates 8 and 11, and the allylic ether 10 display small solvent-polarity effects on the reactivity. The regioselectivity of the singlet oxygen ene reaction is solvent independent for the unfunctionalized alkenes as well as the prenol-type substrates, the latter showing substantial solvent effects on the diastereoselectivity. Pronounced physical quenching is detected only for the allylic alcohols 5 and 6. These results are interpreted in terms of the interactions between singlet oxygen and the allylic hydroxy groups, conformationally promoted by allylic strain which lead either to chemical activation or to physical quenching. The results for substrate 9 in deuterated vs. non-deuterated methanol are in accord with hydrogen bonding between the allylic alcohol and O-1(2), which directs the diastereoselectivity of the ene reaction with chiral allylic alcohols.