Preparation and photophysical properties of a caged kynurenine

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• 作者：Chandan Maitrani^a ; Derren J. Heyes^b ; Sam Hay^b ; Selvanathan Arumugam^a ; Vladimir V. Popik^a ; Robert S. Phillips^a ; ^c ; ^{rsphillips@chem.uga.edu} ; ^plp@uga.edu
• 关键词：Tryptophan metabolism ; Photochemistry ; Caged compound
• 刊名：Bioorganic and Medicinal Chemistry Letters
• 出版年：2012
• 期刊代码：10_0960894x
• 类别：ch
• 出版时间：15 April, 2012
• 卷：22
• 期：8
• 页码：2734-2737
• 文件大小：390 K

摘要

We have prepared l-kyurenine 4-hydroxyphenacyl ester, a caged derivative of l-kynurenine. N^伪-tBOC-l-tryptophan was reacted with 4-hydroxyphenacyl bromide in DMF with K₂CO₃ as the base to give the N^伪-tBOC 4-hydroxyphenacyl ester. The ester was then treated with O₃ in MeOH at 鈭?0 掳C, followed by trifluoroacetic acid in CH₂Cl₂, then aqueous HCl to obtain the caged kynurenine as the dihydrochloride salt. The caged kynurenine is stable as a dry solid in the dark at 鈭?8 掳C, but in aqueous solutions in phosphate buffer at pH 7-8 hydrolyzes rapidly (t_1/2 鈭? min). Solutions in Tris at pH 7 are more stable (t_1/2 >30 min), and solutions in 1 mM HCl are stable for several hours. As expected, the ester is cleaved in microseconds with laser pulses at 355 nm. The caged kynurenine may be useful for preparation of substrate complexes for crystallography or in biological studies on kynurenine.