A highly efficient N,N′-dioxide/Gd(III) complex has been developed for the enantioselective conjugate addition of nitroalkanes to α,β-unsaturated pyrazolamides. Under mild reaction conditions, a series of γ-nitropyrazolamides were obtained in good to excellent yields (up to 99%) with excellent enantioselectivities (up to 99% ee). What’s more, the optically active products could be easily transformed
A chiral nickel DBFOX complex as a bifunctional catalyst for visible-light-promoted asymmetric photoredox reactions
作者:Xiang Shen、Yanjun Li、Zhaorui Wen、Shi Cao、Xinyi Hou、Lei Gong
DOI:10.1039/c8sc01219a
日期:——
The enantioselective photoredox reaction of α,β-unsaturated carbonyl compounds and tertiary/secondary α-silylamines was enabled by a readily available single NiII–DBFOX catalyst (DBFOX = 4,6-bis((R)-4-phenyl-4,5-dihydrooxazol-2-yl)dibenzo[b,d]furan) under visible light conditions. The non-precious chiral catalyst is involved in the photochemical process to initiate single electron transfer and at the
α,β-不饱和羰基化合物和叔/仲α-甲硅烷基胺的对映选择性光氧化还原反应是通过易于获得的单一Ni II –DBFOX催化剂实现的(DBFOX = 4,6-bis(( R )-4-苯基-4, 5-二氢恶唑-2-基)二苯并[ b , d ]呋喃)在可见光条件下。非贵重的手性催化剂参与光化学过程以引发单电子转移,同时为随后的自由基转变提供良好组织的手性环境。手性 γ-氨基羧酸衍生物和 γ-内酰胺的形成获得了良好至优异的对映选择性 (80–99% ee)。
Asymmetric Catalytic Synthesis of Hexahydropyrrolo‐isoquinolines via Three‐Component 1,3‐Dipolar‐Cycloaddition
Highly enantioselective Michael addition of α-nitroacetate to α,β-unsaturated pyrazolamide catalyzed by a bifunctional squaramide
作者:Yingying Liu、Ling Ye、Zhichuan Shi、Xuejun Yang、Zhigang Zhao、Xuefeng Li
DOI:10.1002/chir.23023
日期:2018.12
A highly enantioselective (91‐ > 99% ee) Michaeladdition of α‐nitroacetate to α,β‐unsaturated pyrazolamide was developed in the presence of a bifunctional squaramide. Satisfactory isolated yields (42%‐99%) have been achieved with a wide range of α,β‐unsaturated pyrazolamides, albeit acceptor of this type displayed poor reactivity in the precedent reports. The adducts resulting from this protocol are
Enantioselective synthesis of fused dihydropyranones via squaramide-catalyzed Michael addition/lactonization cascade reaction
作者:Jialing Xian、Lin Chen、Ling Ye、Yin Sun、Zhichuan Shi、Zhigang Zhao、Xuefeng Li
DOI:10.1016/j.tet.2019.03.007
日期:2019.4
A highly enantioselective (49–99% ee) Michael addition/lactonization cascade process has been developed to construct 3,4-dihydropyran-2-one in the presence of a bifunctional squaramide. Various α,β-unsaturated N-acyl heterocycles were well tolerated and afforded 3,4-dihydropyran-2-ones in moderate to excellent isolated yields (50–99%). Both cyclic and acyclic β-diketones functioned as appropriate donors