Stanford Martin W, Bismuto Alessandro, Cowley Michael J
School of Chemistry, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh, EH9, 3FJ, United Kingdom.
Chemistry. 2020 Aug 6;26(44):9855-9858. doi: 10.1002/chem.202000897. Epub 2020 Jul 2.
Hydroboration is an emerging method for mild and selective reduction of carbonyl compounds. Typically, transition-metal or reactive main-group hydride catalysts are used in conjunction with a mild reductant such as pinacolborane. The reactivity of the main-group catalysts is a consequence of the nucleophilicity of their hydride ligands. Silicon hydrides are significantly less reactive and are therefore not efficient hydroboration catalysts. Here, a readily prepared silyl anion is reported to be an effective initiator for the reduction of aldehydes and ketones requiring mild conditions, low catalyst loadings and with a good substrate scope. The silyl anion it is shown to activate HBpin to generate a reactive borohydride in situ which reacts with aldehydes and ketones to afford the hydroboration product.
硼氢化反应是一种用于温和且选择性地还原羰基化合物的新兴方法。通常，过渡金属或活性主族氢化物催化剂会与诸如频哪醇硼烷这样的温和还原剂一起使用。主族催化剂的反应活性是其氢化物配体亲核性的结果。硅氢化物的反应活性明显较低，因此不是高效的硼氢化反应催化剂。在此，据报道一种易于制备的硅烷基阴离子是在温和条件、低催化剂负载量以及良好底物范围下还原醛和酮的有效引发剂。已表明该硅烷基阴离子能活化频哪醇硼烷原位生成一种活性硼氢化物，其与醛和酮反应得到硼氢化产物。
