Removal of the Pyridine Directing Group from 伪-Substituted N-(Pyridin-2-yl)piperidines Obtained via Directed Ru-Catalyzed sp3 C鈥揌 Functionalization

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• 作者：Veerle Smout ; Aldo Peschiulli ; Stefan Verbeeck ; Emily A. Mitchell ; Wouter Herrebout ; Patrick Bultinck ; Christophe M. L. Vande Velde ; Didier Berthelot ; Lieven Meerpoel ; Bert U. W. Maes
• 刊名：Journal of Organic Chemistry
• 出版年：2013
• 出版时间：October 4, 2013
• 年：2013
• 卷：78
• 期：19
• 页码：9803-9814
• 全文大小：503K
• 年卷期：v.78,no.19(October 4, 2013)
• ISSN：1520-6904

文摘

Two strategies, 鈥渉ydrogenation鈥揾ydride reduction鈥?and 鈥渜uaternization鈥揾ydride reduction鈥? are reported that make use of mild reaction conditions (room temperature) to efficiently remove the N-pyridin-2-yl directing group from a diverse set of C-2-substituted piperidines that were synthesized through directed Ru-catalyzed sp³ C鈥揌 functionalization. The deprotected products are obtained in moderate to good overall yields irrespective of the strategy followed, indicating that both methods are generally equally effective. Only in the case of 2,6-disubstituted piperidines, could the 鈥渜uaternization鈥揾ydride reduction鈥?strategy not be used. The 鈥渉ydrogenation鈥揾ydride reduction鈥?protocol was successfully applied to trans- and cis-2-methyl-N-(pyridin-2-yl)-6-undecylpiperidine in a short synthetic route toward (卤)-solenopsin A (trans diastereoisomer) and (卤)-isosolenopsin A (cis diastereoisomer). The absolute configuration of the enantiomers of these fire ant alkaloids could be determined via VCD spectroscopy.