Asymmetric Hydrogenation of Ketones and Enones with Chiral Lewis Base Derived Frustrated Lewis Pairs. (27th January 2020)

• Record Type: Journal Article
• Authors: Gao, Bochao; Feng, Xiangqing; Meng, Wei; Du, Haifeng
• Is Part Of: Angewandte Chemie. Volume 132:Number 11(2020)
• Page Start: 4528
• Page End: 4534
• Publication Date: 2020-01-27
• Subjects: Frustrierte Lewis-Paare -- Hydrierungen -- Lewis-Base -- Ketone -- Reaktionsmechanismen; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.201914568
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: The concept of frustrated Lewis pairs (FLPs) has been widely applied in various research areas, and metal‐free hydrogenation undoubtedly belongs to the most significant and successful ones. In the past decade, great efforts have been devoted to the synthesis of chiral boron Lewis acids. In a sharp contrast, chiral Lewis base derived FLPs have rarely been disclosed for the asymmetric hydrogenation. In this work, a novel type of chiral FLP was developed by simple combination of chiral oxazoline Lewis bases with achiral boron Lewis acids, thus providing a promising new direction for the development of chiral FLPs in the future. These chiral FLPs proved to be highly effective for the asymmetric hydrogenation of ketones, enones, and chromones, giving the corresponding products in high yields with up to 95 % ee . Mechanistic studies suggest that the hydrogen transfer to simple ketones likely proceeds in a concerted manner. Abstract : Ein neues Paar : Eine neue Art von frustriertem Lewis‐Paar wurde aus chiralen Oxazolin‐Lewis‐Basen und achiralen Bor‐Lewis‐Säuren entwickelt. Die chirale Lewis‐Base wirkt als dirigierende Komponente für die asymmetrische Induktion. Eine enantioselektive Hydrierung von Ketonen und Enonen wurde realisiert, welche die Produkte in hohen Ausbeuten mit bis zu 95 % ee lieferte.