aerobic oxidative cyclization of β,γ-unsaturated hydrazones for the preparation of pyrazole derivatives has been developed. The hydrazonyl radical promoted the cyclization, along with a concomitant C═Cbondcleavage of β,γ-unsaturated hydrazones. This process has been verified via several control experiments, including a radical-trapping study, an 18O-labeling method, and the identification of the possible
highly efficient Pd/Xiang-Phos catalyzedenantioselective carboetherification of alkenyl oximes with either aryl or alkenyl halides, delivering various chiral 3,5-disubstituted and 3,5,5-trisubstituted isoxazolines in good yields with up to 97 % ee. The sterically bulky and electron-rich (S,Rs)-NMe-X2 ligand is responsible for the excellent reactivities and enantioselectivities. The salient features of this
Palladium-Catalyzed Cross-Coupling of Unactivated Alkenes with Acrylates: Application to the Synthesis of the C13-C21 Fragment of Palmerolide A
作者:Zhen-Kang Wen、Yun-He Xu、Teck-Peng Loh
DOI:10.1002/chem.201201806
日期:2012.10.15
Diene to meet: A palladium‐catalyzed cross‐coupling reaction between alkyl‐substitutedolefins and acrylates gives the corresponding butadienes in moderate yield and stereoselectivity. This atom‐economical reaction, which forms C–C bonds, tolerates a wide range of allylic and homoallylic alcohols, and acrylates (see scheme; TIPS =triisopropylsilyl). The methodology was applied to the synthesis of the
Accessing novel fluorinated heterocycles with the hypervalent fluoroiodane reagent by solution and mechanochemical synthesis
作者:William Riley、Andrew C. Jones、Kuldip Singh、Duncan L. Browne、Alison M. Stuart
DOI:10.1039/d1cc02587b
日期:——
A new and efficient strategy for the rapid formation of novel fluorinated tetrahydropyridazines and dihydrooxazines has been developed by fluorocyclisation of β,γ-unsaturatedhydrazones and oximes with the fluoroiodane reagent. Mechanochemical synthesis delivered fluorinated tetrahydropyridazines in similar excellent yields to conventional solution synthesis, whereas fluorinated dihydrooxazines were
Synthesis of 2-hydroxytetrahydrofurans by Wacker-type oxidation of 1,1-disubstituted alkenes
作者:Rina Tanaka、Saki Komori、Yuhei Shimizu、Yasutaka Kataoka、Yasuyuki Ura
DOI:10.1039/d1ob02277f
日期:——
1,1-Disubstituted alkenes feature high steric hindrance, which renders their Wacker-type oxidation difficult. We demonstrate the stereoselective synthesis of 2-hydroxytetrahydrofurans via the Wacker-type oxidation of 3-methyl-3-buten-1-ols by using a PdCl2(MeCN)2/NO/BQ catalyst system under 1 atm O2 in H2O or H2O/DMF.
1,1-二取代烯烃具有高位阻,这使得它们的瓦克型氧化变得困难。我们通过使用 PdCl 2 (MeCN) 2 /NO/BQ 催化剂体系在 H 2中的 1 atm O 2下通过Wacker 型氧化 3-methyl-3-buten-1-ols展示了 2-羟基四氢呋喃的立体选择性合成。O或H 2 O/DMF。