A chiral Lewisbaseorganocatalyzedenantioselectivehydrosilylation of 1,4-benzoxazines is presented. The reactions afforded various enantioenriched 3-substituted dihydro-2 H -1,4-benzoxazines with high yields (up to 98%) in moderate enantioselectivities (up to 87% ee).
提出了一种手性路易斯碱有机催化的 1,4-苯并恶嗪的对映选择性氢化硅烷化。该反应以中等对映选择性(高达 87% ee)的高产率(高达 98%)提供了各种对映体富集的 3-取代二氢-2 H -1,4-苯并恶嗪。
Cooperative Iron-Brønsted Acid Catalysis: Enantioselective Hydrogenation of Quinoxalines and 2 <i>H</i>-1,4-Benzoxazines
together! A selective Fe‐catalysed enantioselective reduction of quinoxalines and benzoxazines with hydrogen is demonstrated. Key to success is the combination of a chiral Brønsted acid and a well‐defined non‐chiral Fe hydrogenation catalyst. This methodology constitutes an attractive and environmentally favourable alternative to well‐established asymmetric hydrogenations by using precious‐metal‐based catalysts
A series of tunable and regenerable biomimetic hydrogen sources, 4,5-dihydropyrrolo[1,2-a]quinoxalines, have been synthesized and applied in biomimetic asymmetric hydrogenation of 3-aryl-2H-benzo[b][1,4]oxazines and 1-alkyl-3-aryl-quinoxalin-2(1H)-ones, providing the chiral amines with up to 92% and 89% ee, respectively.
合成了一系列可调和可再生的仿生氢源4,5-二氢吡咯并[1,2- a ]喹喔啉,并将其用于3-芳基-2 H-苯并[ b ] [1,4]的仿生不对称加氢。恶嗪和1-烷基-3-芳基-喹喔啉-2(1 H)-酮,分别为手性胺提供高达92%和89%的ee。
Iridium-Catalyzed Asymmetric Hydrogenation of 3-Substituted 2H-1,4-Benzoxazines
The highly enantioselective hydrogenation of 3-aryl-2H-1,4-benzoxazines was achieved using the (cyclooctadiene)iridium chloride dimer/(S)-SegPhos/iodine [Ir(COD)Cl]2/(S)-SegPhos/I2} system as catalyst with up to 92% ee. The 3-styryl-2H-1,4-benzoxazine derivatives were also hydrogenated by the iridium catalyst and Pd/C in two consecutive steps whereby 93–95% ee values were obtained.
使用(环辛二烯)铱氯化二聚物/(S)-SegPhos /碘[Ir(COD)Cl] 2 /(S)-SegPhos实现对3-芳基2 H -1,4-苯并恶嗪的高度对映选择性氢化/ I 2 }体系作为催化剂,ee最高可达92%。3-styryl-2 H -1,4-苯并恶嗪衍生物还通过铱催化剂和Pd / C在两个连续的步骤中进行氢化,从而获得93-95%ee值。
Asymmetric Transfer Hydrogenation of Heterocyclic Compounds in Continuous Flow Using an Immobilized Chiral Phosphoric Acid as the Catalyst
作者:Pavel Nagorny、Oleksii Zhelavskyi、Yin-Jia Jhang
DOI:10.1055/a-2085-5256
日期:2023.8
This manuscript describes transfer hydrogenation of bicyclic nitrogen-containing heterocycliccompoundsusing the immobilized chiral phosphoric acid catalyst (R)-PS-AdTRIP in batch and continuous flow. A significant improvement in enantioselectivities is achieved in continuous flow with a fluidized bed reactor packed with (R)-PS-AdTRIP when the flow rate is increased from 0.2 mL/min to 2.0–2.5 mL/min
该手稿描述了使用固定化手性磷酸催化剂 ( R )-PS-AdTRIP 以间歇和连续流进行双环含氮杂环化合物的转移氢化。当流速从 0.2 mL/min 增加到 2.0–2.5 mL/min 时,使用填充 ( R )-PS-AdTRIP的流化床反应器在连续流动中实现了对映选择性的显着改善。优化的连续流动条件始终比使用 2 mol% ( R )-PS-AdTRIP 的间歇转移氢化提供高 4–6% ee 的选择性,并用于使用相同的流化床反应器生成多种手性产物。