Chemoselective Ketone Synthesis by the Strontium‐mediated Alkylation or Arylation of N , N ‐Dimethylamides or Urea
Chemoselective Ketone Synthesis by the Strontium‐mediated Alkylation or Arylation of N , N ‐Dimethylamides or Urea
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通过锶介导的 N,N-二甲基酰胺或尿素烷基化或芳基化化学选择性酮合成
DOI：
10.1002/ajoc.202000389
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发表时间：
2020
影响因子：
2.7
通讯作者：
Ueno Masaharu
中科院分区：
文献类型：
--
作者：
Miyoshi Norikazu;Kimura Shodai;Kubo Shigeki;Ohmura Satoshi D.;Ueno Masaharu
通过有机金属试剂加成到酰胺上来合成酮的研究由来已久。在许多情况下，有必要控制溶剂、反应温度，并且对于酰胺和有机金属试剂的每种组合坚持严格的亲核化学计量。锶的电负性与锂相当，但离子半径更大，可能显示出具有单烷基化特征的高反应性。在这里，我们表明，在一般温和的温度条件下，各种N，N-二甲基酰胺衍生物与烷基碘的单烷基化反应顺利进行，得到酮。通过这种方法，不仅芳香族酰胺，而且α-带质子的脂肪族酰胺是酮合成的合适底物。此外，我们发现，四甲基脲，通常是一个不良的亲电试剂，也反应，以良好的产率和优异的选择性提供二苯甲酮。
Ketone synthesis via the addition of organometallic reagents to amides has long been investigated. In many cases, it is necessary to control the solvent, reaction temperature, and adhere to strict nucleophile stoichiometry for each combination of amide and organometallic reagent. Strontium, with an electronegativity comparable to lithium but a larger ionic radius, may display high reactivity with the characteristics of monoalkylation. Here, we show that the monoalkylation of variousN,N‐dimethylamide derivatives with alkyl iodides to afford the ketones proceeds smoothly under generally mild temperature conditions. By this method, not only aromatic amides but also α‐proton‐bearing aliphatic amides were suitable substrates for ketone synthesis. In addition, we found that tetramethylurea, typically a poor electrophile, also reacted to afford benzophenone in good yield with excellent selectivity.