Sterically Congested Adamantylnaphthalene Quinone Methides

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• 作者：Jelena Veljkovi膰 ; Lidija Uzelac ; Kre拧imir Mol膷anov ; Kata Mlinari膰-Majerski ; Marijeta Kralj ; Peter Wan ; Nikola Basari膰
• 刊名：The Journal of Organic Chemistry
• 出版年：2012
• 出版时间：May 18, 2012
• 年：2012
• 卷：77
• 期：10
• 页码：4596-4610
• 全文大小：587K
• 年卷期：v.77,no.10(May 18, 2012)
• ISSN：1520-6904

文摘

Five new (2-adamantyl)naphthol derivatives (5鈥?b>9, quinone methide precursors, QMP) were synthesized and their photochemical reactivity was investigated by preparative photolyses, fluorescence spectroscopy, and laser flash photolysis (LFP). Excitation of QMP 5 to S₁ leads to efficient excited state intramolecular proton transfer (ESIPT) coupled with dehydration, giving quinone methide QM5 which was characterized by LFP (in CH₃CN鈥揌₂O, 位_max = 370 nm, 蟿 = 0.19 ms). On irradiation of QMP 5 in CH₃OH鈥揌₂O (4:1), the quantum yield of methanolysis is 桅 = 0.70. Excitation of naphthols QMP 6鈥?b>8 to S₁ in CH₃CN leads to photoionization and formation of naphthoxyl radicals. In a protic solvent, QMP 6鈥?b>8 undergo solvent-assisted PT giving QM6 or zwitterion QM8 that react with nucleophiles delivering adducts, but with a significantly lower quantum efficiency. QMP 9 in a protic solvent undergoes two competitive processes, photosolvolysis via QM9 and solvent-assisted PT to carbon atom of the naphthalene giving zwitterion. QM9 has been characterized by LFP (in CH₃CN鈥揌₂O, 位_max > 600 nm, 蟿 = 0.9 ms). In addition to photogenerated QMs, two stable naphthalene QMs, QM10 and QM11 were synthesized thermally and characterized by X-ray crystallography. QM10 and QM11 do not react with H₂O but undergo acid-catalyzed fragmentation or rearrangement. Antiproliferative activity of 5鈥?b>9 was investigated on three human cancer cell lines. Exposure of MCF-7 cells treated with 5 to 300 nm irradiation leads to an enhanced antiproliferative effect, in accordance with the activity being due to the formation of QM5.