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。
Remarkable Ligand Effect on Rh-Catalyzed C–H-Active [3 + 2] Annulation of Ketimines and Alkynes
作者:Yan Shi、Yong Fang、Xu Zhao、Chengfeng Zhu、Xiang Wu、Xiaoming Yang、Yunfei Luo
DOI:10.1021/acs.orglett.0c01768
日期:2020.6.19
Externally added ligands were first found to have a significant impact on the Rh-catalyzed C–H-active [3 + 2] annulation of ketimines and alkynes. Olefin ligands have shown remarkable promotion effect for this reaction. The olefin promoted the reaction by increasing both the turnover rate and conversion of [Cp*RhCl2]2 in the formation of rhodacycle in the C–H activation step.
Regio- and Diastereoselective [3 + 2]-Spiroannulation of Benzoxazines with Chalcones: A Rh(III)-Catalyzed Redox-Neutral Approach to α-Aroyl Spiro-Indanamines
作者:Writhabrata Sarkar、Koushik Naskar、Shantonu Roy、Imtiaj Mondal、Sudip Karmakar、Aniket Mishra、Indubhusan Deb
DOI:10.1021/acs.joc.2c00974
日期:2022.8.5
We report an atom-economic Rh(III)-catalyzed [3 + 2]-spiroannulation reaction between cyclic ketimines and α,β-unsaturated carbonyl compounds, allowing the synthesis of novel spirocycles with concomitant generation of three stereogenic centers in one pot. The reaction does not require any silver additives or external oxidants and is believed to proceed in a redox-neutral manner. A broad substrate scope
Efficient synthesis of spirooxazine-pyrans <i>via</i> rhodium-catalyzed [3+3] cascade spiroannulation of benzoxazines with 1-diazonaphthalen-2(1<i>H)</i>-ones
作者:Junwei Huang、Xuelin Yue、Yijie Gao、Yadong Feng、Xiuling Cui
DOI:10.1039/d3nj01894f
日期:——
A mild and efficient tool to construct structurally diverse N/O spiroheterocycles via Rh(III)-catalyzed [3+3] cascade spiroannulation of benzoxazines with 1-diazonaphthalen-2(1H)-ones has been developed. The desired spirooxazine-pyrans could be afforded in up to 99% yields at room temperature within 30 min. This transformation involves C–H activation, tautomerization, and intramolecular nucleophilic
开发了一种温和有效的工具,可通过Rh( III ) 催化的苯并恶嗪与 1-重氮萘-2(1 H )-酮的 [3+3] 级联螺环化反应构建结构多样的 N/O 螺杂环。在室温下,30 分钟内即可得到所需的螺恶嗪-吡喃,收率高达 99%。这种转化涉及“一锅”方式的 C-H 激活、互变异构和分子内亲核加成。此外,该催化体系还具有高效、原子经济、宽官能团耐受性和极其温和的反应条件等特点。