Ramachandran P Veeraraghavan, Alawaed Abdulkhaliq A, Hamann Henry J
Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States.
J Org Chem. 2022 Oct 7;87(19):13259-13269. doi: 10.1021/acs.joc.2c01744. Epub 2022 Sep 12.
Investigation of a variety of Lewis acids for the hydroboration-hydrolysis (reduction) of ketones with amine-boranes has revealed that catalytic (10 mol %) titanium tetrachloride (TiCl) in diethyl ether at room temperature immensely accelerates the reaction of ammonia borane. The product alcohols are produced in good to excellent yields within 30 min, even with ketones which typically requires 24 h or longer to reduce under uncatalyzed conditions. Several potentially reactive functionalities are tolerated, and substituted cycloalkanones are reduced diastereoselectively to the thermodynamic product. A deuterium labeling study and B NMR analysis of the reaction have been performed to verify the proposed hydroboration mechanism.
对多种用于胺硼烷对酮进行硼氢化-水解（还原）反应的路易斯酸的研究表明，在室温下于二乙醚中使用催化量（10 mol%）的四氯化钛（TiCl₄）能极大地加速氨硼烷的反应。即使是在未催化条件下通常需要24小时或更长时间才能还原的酮，在30分钟内也能以良好至优异的产率生成产物醇。该反应能耐受几种潜在的反应性官能团，并且取代环烷酮能非对映选择性地还原为热力学产物。已进行了氘标记研究和该反应的¹¹B NMR分析，以验证所提出的硼氢化机理。
