Heinz Michael, Weiss Gregor, Shizgal Grigoriy, Panfilova Anastasia, Gansäuer Andreas
Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Gerhard-Domagk-Straße 1, 53121, Bonn, Germany.
Angew Chem Int Ed Engl. 2023 Sep 18;62(38):e202308680. doi: 10.1002/anie.202308680. Epub 2023 Aug 17.
We describe a unique catalytic system with an efficient coupling of Ti- and Cr-catalysis in a reaction network that allows the use of [BH ] as stoichiometric hydrogen atom and electron donor in catalytic radical chemistry. The key feature is a relay hydrogen atom transfer from [BH ] to Cr generating the active catalysts under mild conditions. This enables epoxide reductions, regiodivergent epoxide opening and radical cyclizations that are not possible with cooperative catalysis with radicals or by epoxide reductions via Meinwald rearrangement and ensuing carbonyl reduction. No typical S 2-type reactivity of [BH ] salts is observed.
我们描述了一种独特的催化体系，在一个反应网络中实现了钛催化和铬催化的高效偶联，该反应网络允许在催化自由基化学中使用[BH]作为化学计量的氢原子和电子供体。关键特征是在温和条件下，氢原子从[BH]中继转移到铬上，生成活性催化剂。这使得环氧化物还原、区域发散性环氧化物开环和自由基环化成为可能，而这些反应通过自由基协同催化或经由迈因瓦尔德重排及随后的羰基还原进行环氧化物还原是无法实现的。未观察到[BH]盐典型的S2型反应活性。
