Asymmetric synthesis of tetrahydropyran[3,2-c]quinolinones via an organocatalyzed formal [3 + 3] annulation of quinolinones and MBH 2-naphthoates of nitroolefin
摘要:
An efficient asymmetric and enantio-swithchable organocatalytic [3 + 3] annulation reaction using MBH-2-naphthoates of nitroalkenes and 4-hydroxyquinolin-2(1H)-ones has been developed. Densely substituted tetrahydropyrano[3,2-c]quinolinones scaffolds with two adjacent stereogenic centers are obtained with high yield (up to 95% yield) and good stereoselectivities (up to >20:1 dr and 96% ee) in an enantio-switchable manner. Furthermore, gram scale synthesis was achieved and the nitro group could easily transform into an amino group without any appreciable loss in the diastereo- and enantioselectivity. (C) 2019 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.
Mimicking transition metals in borrowing hydrogen from alcohols
作者:Ananya Banik、Jasimuddin Ahmed、Swagata Sil、Swadhin K. Mandal
DOI:10.1039/d1sc01681d
日期:——
Borrowinghydrogen from alcohols, storing it on a catalyst and subsequent transfer of the hydrogen from the catalyst to an in situ generated imine is the hallmark of a transition metal mediated catalytic N-alkylation of amines. However, such a borrowinghydrogen mechanism with a transition metal free catalytic system which stores hydrogen molecules in the catalyst backbone is yet to be established
从醇中借用氢气,将其储存在催化剂上,然后将氢气从催化剂转移到原位生成的亚胺,这是过渡金属介导的胺催化N-烷基化的标志。然而,这种在催化剂主链中储存氢分子的无过渡金属催化系统的借氢机制尚未建立。在此,我们证明苯酚基配体可以模仿过渡金属在储存和转移氢分子中的作用,从而导致借氢介导的醇类苯胺烷基化,包括广泛的底物范围。通过各种光谱技术、氘标记实验和 DFT 研究表征几种中间体,对机制途径进行了仔细检查,得出的结论是,基于苯酚基的主链通过脱芳构化过程依次添加 H + 、 H˙ 和一个电子,随后将其用作还原剂。相当于催化方式中的C-N双键。
Iron-Catalyzed Synthesis of Secondary Amines: On the Way to Green Reductive Aminations
reaction sequence a primary amine is formed in situ from the corresponding nitro compound. Reversible condensation with aldehydes forms the respective imines, which are finally reduced to the desired secondary amine. This synthesis of secondary amines is atom‐economical and environmentally attractive using cheap and readily available organic compounds as starting materials.
An ionic 2,6-bis(imidazo[1,2-α]pyridin-2-yl)pyridine-based N^N^N pincer ruthenium(II) complex exhibited high efficiency in the C–N bond formation between amines and alcohols by the “borrowing hydrogen” (BH) or “hydrogen autotransfer” (HA) concept. The synthetic protocol selectively generated monoalkylated amines without formation of tertiary amines during the reaction. The unique selectivity enabled
sustainable or green reaction that has received a lot of attention in recent years and is preferentially catalyzed by Ir or Ru complexes is the alkylation of amines by alcohols. It is based on the borrowing hydrogen or hydrogen autotransfer concept. Herein, we report on the Co‐catalyzed alkylation of aromaticamines by alcohols. The reaction proceeds undermildconditions, and selectively generates monoalkylated
Iridium complexes with ligands of 1,8-Naphthyridine-2-carboxylic acid derivatives-preparation and catalysis
作者:Ming Li、Yen-Pin Hsu、Yi-Hung Liu、Shie-Ming Peng、Shiuh-Tzung Liu
DOI:10.1016/j.jorganchem.2020.121537
日期:2020.11
8-naphthyridine(Np)-2-carboxylic derivatives L1-L3 [L1 = Np-2-COOH, L2 = Np-2-CONH2, L3 = Np-2-CONHCH2Py] with [Ir(COD)(µ-OMe)]2 yielded the corresponding complexes [Ir(COD)(Ln)] (1~3, n = 1~3, respectively). The potential tridentate L3 behaves as a bidentate donor in the complex 3. Treatment of L1 with [Ir(COD)Cl]2 under nitrogen atmosphere gave a Ir(III) hydride complex [Ir(COD)(L1)HCl] (4). However, carrying