Reduction of N-allylamides by LiAlH4: unexpected attack of the double bond with mechanistic studies of product and byproduct formation.
Reduction of N-allylamides by LiAlH4: unexpected attack of the double bond with mechanistic studies of product and byproduct formation.
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DOI：
10.1021/jo501907v
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发表时间：
2014-10
期刊：
影响因子：
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通讯作者：
Birk Thiedemann;C. Schmitz;A. Staubitz
中科院分区：
文献类型：
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作者：
Birk Thiedemann;C. Schmitz;A. Staubitz
用LiAlH4还原仲烯丙基酰胺可导致双键的伴随还原。以前，在危险溶剂中过量的LiAlH4用于还原。这项工作讨论了优化的反应条件tBuOMe作为一种安全的溶剂，只有1.5倍过量的LiAlH4，在大多数情况下没有减少的双键。(1)H（2）D NMR谱研究为酰胺和双键的还原机理提供了证据：酰胺还原一般先于双键还原。空间位阻烯丙基酰胺是一个例外。它们在较高温度下还原得相当慢，并且在酰胺还原完成之前观察到双键还原。
The reduction of secondary allyl amides with LiAlH4 can lead to a concomitant reduction of the double bond. Previously, an excess of LiAlH4 in hazardous solvents was used for the reduction. This work discusses optimized reaction conditions in tBuOMe as a safe solvent, with only a 1.5-fold excess of LiAlH4, without reduction of the double bond in most cases. (1)H and (2)D NMR spectroscopic studies give evidence for the mechanism of the reduction of the amide as well as the double bond: Amide reduction generally precedes double bond reduction. Sterically hindered allylamides are an exception. They are reduced considerably more slowly at higher temperatures, and double bond reduction is observed before amide reduction has gone to completion.