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立体选择性亲电氟化 2-脱氧核糖内酯:全相应的 2-脱氧-2-氟代内酯和 2'-脱氧-2'-氟代 NAD+的合成。

Diastereocontrolled electrophilic fluorinations of 2-deoxyribonolactone: syntheses of all corresponding 2-deoxy-2-fluorolactones and 2'-deoxy-2'-fluoro-NAD+s.

机构信息

Department of Pharmacology, Weill Medical College of Cornell University, 1300 York Avenue, New York, New York 10065, USA.

出版信息

J Org Chem. 2009 Aug 21;74(16):5779-89. doi: 10.1021/jo900637f.

Abstract

Methods to construct 2'-deoxy-2'-fluoro nucleosides have undergone limited improvement in the last 20 years in spite of the substantially increased value of these compounds as pharmaceuticals and as tools for studying biological processes. We herein describe a consolidated approach to synthesize precursors to these commercially and scientifically valuable compounds via diastereocontrolled fluorination of the readily available precursor 2-deoxy-d-ribonolactone. With employment of appropriate sterically bulky silyl protecting groups at the 3 and 5 positions, controlled electrophilic fluorination of the Li-ribonolactone enolate by N-fluorodibenzenesulfonamide yielded the corresponding 2-deoxy-2-fluoroarabinolactone in high isolated yield (72%). The protected 2-deoxy-2,2-difluororibonolactone was obtained similarly in high yield from a second round of electrophilic fluorination (two steps, 51% from protected ribonolactone starting material). Accomplishment of the difficult ribofluorination of the lactone was achieved by the directive effects of a diastereoselectively installed alpha-trimethylsilyl group. Electrophilic fluorination of a protected 2-deoxy-2-trimethylsilylarabinolactone via enolate generation provided the protected 2-deoxy-2-fluororibolactone as the exclusive fluorinated product. The reaction also yielded the starting material, the desilylated protected 2-deoxyribonolactone, which was recycled to provide a 38% chemical yield of the fluorinated product (versus initial protected ribonolactone) after consecutive silylation and fluorination cycles. Using our fluorinated sugar precursors, we prepared the 2'-fluoroarabino-, 2'-fluororibo-, and 2',2'-difluoronicotinamide adenine dinucleotides (NAD(+)) of potential biological interest. These syntheses provide the most consolidated and efficient methods for production of sugar precursors of 2'-deoxy-2'-fluoronucleosides and have the advantage of utilizing an air-stable electrophilic fluorinating agent. The fluorinated NAD(+)s are anticipated to be useful for studying a variety of cellular metabolic and signaling processes.

摘要

尽管这些化合物作为药物和研究生物过程的工具的价值大大增加,但在过去的 20 年中,构建 2'-脱氧-2'-氟核苷的方法仅得到了有限的改进。在此,我们描述了一种通过 readily available precursor 2-脱氧-d-核糖醇内酯的非对映选择性氟化来合成这些具有商业和科学价值的化合物前体的综合方法。通过在 3 位和 5 位使用适当的大位阻硅保护基,N-氟二苯甲脒对 Li-核糖醇内酯烯醇化物的亲电氟化得到了相应的 2-脱氧-2-氟阿拉伯醇内酯,收率高(72%)。通过第二轮亲电氟化(两步,从保护的核糖醇内酯起始原料计,收率为 51%),也以高收率得到了相应的保护的 2-脱氧-2,2-二氟核糖醇内酯。内酯的核糖氟化是通过立体选择性安装的α-三甲基甲硅烷基的定向效应来实现的。通过烯醇化物生成对保护的 2-脱氧-2-三甲基甲硅烷基阿拉伯醇内酯进行亲电氟化,得到了保护的 2-脱氧-2-氟核糖醇内酯作为唯一的氟化产物。该反应还得到了起始原料,即脱硅保护的保护的 2-脱氧核糖醇内酯,其在连续的硅化和氟化循环后,以 38%的化学收率(相对于初始保护的核糖醇内酯)回收,用于制备氟化产物。使用我们的氟化糖前体,我们制备了具有潜在生物学意义的 2'-氟阿拉伯糖、2'-氟核糖和 2',2'-二氟尼克酰胺腺嘌呤二核苷酸(NAD(+))。这些合成提供了制备 2'-脱氧-2'-氟核苷糖前体的最综合和有效的方法,并具有利用稳定的亲电氟化剂的优势。预期氟化的 NAD(+)可用于研究各种细胞代谢和信号转导过程。

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