Scope and Limitations of Lithium-Ethylenediamine-THF-Mediated Cleavage at the α-Position of Aromatics: Deprotection of Aryl Methyl Ethers and Benzyl Ethers under Mild Conditions
作者:Takeshi Sugai、Takeyuki Shindo、Yasuaki Fukuyama
DOI:10.1055/s-2004-815977
日期:——
and limitation of lithium-ethylenediamine-THF-mediated reductive bond cleavage at the α-position of aromatics were examined. Very mild conditions such as lithium metal (5 equiv) and ethylenediamine (7 equiv) in oxygen-free THF were quite effective for the demethylation of aromatic ethers even at as low as -10 °C. Allyl benzyl ethers were also deprotected under these conditions with very little change
考察了锂-乙二胺-THF介导的芳烃α位还原键断裂的范围和局限性。即使在低至 -10 °C 的条件下,无氧 THF 中的锂金属(5 equiv)和乙二胺(7 equiv)等非常温和的条件对芳族醚的去甲基化也非常有效。烯丙基苄基醚也在这些条件下脱保护,烯丙醇部分几乎没有变化。通过这项研究,开发了 2,6-二甲基苄基 (m-xylylmethyl, MXM) 基团作为苄基的替代物,在上述还原条件下易于裂解。