Organocatalytic Enantioselective Michael–Acetalization–Reduction–Nef Reaction for a One-Pot Entry to the Functionalized Aflatoxin System. Total Synthesis of (−)- Dihydroaflatoxin D<sub>2</sub> and (−)- and (+)-Microminutinin
作者:Wei-Lun Huang、Arun Raja、Bor-Cherng Hong、Gene-Hsiang Lee
DOI:10.1021/acs.orglett.7b01473
日期:2017.7.7
enantioselective synthesis of the aflatoxin system with multiple stereocenters via a sequence of organocatalytic Michael–acetalization–reduction–Nef reactions that proceed with high enantioselectivities (90–99% ee). The one-pot reaction sequence provides a facile entry to the aflatoxin system, including dihydroaflatoxin D2, which includes a formal total synthesis of aflatoxin B2. The first total synthesis of (−)-
phosphine-catalyzed asymmetric dearomative [3+2] cycloaddition of 2-nitrobenzofurans with aldehyde-derived Morita–Baylis–Hillman (MBH) carbonates or allenoate was developed. The reaction with MBH carbonates resulted in a series of cyclopentabenzofurans containing three contiguous stereocenters with good to high yields, diastereoselectivities and enantioselectivities. The use of allenoate also gave the target product
Chemoselective N-Heterocyclic Carbene-Catalyzed Cascade of Enals with Nitroalkenes
作者:Zijun Wu、Xu Wang、Fangyi Li、Jicheng Wu、Jian Wang
DOI:10.1021/acs.orglett.5b01692
日期:2015.7.17
An unprecedented N-heterocycliccarbenecatalyzed chemoselective and enantioselective cascade reaction of enals with nitroalkenes has been developed. A wide range of enantioenriched dihydrocoumarins has been prepared, and the reaction goes through an enolate intermediate generated under a catalytic process.
Regio‐ and Stereoselective Cascade of β,γ‐Unsaturated Ketones by Dipeptided Phosphonium Salt Catalysis: Stereospecific Construction of Dihydrofuro‐Fused [2,3‐b] Skeletons
作者:Hongkui Zhang、Jiajia He、Yayun Chen、Cheng Zhuang、Chunhui Jiang、Kai Xiao、Zhishan Su、Xiaoyu Ren、Tianli Wang
DOI:10.1002/anie.202106046
日期:2021.9
heterocyclic molecules in high yields with excellent stereoselectivities. Moreover, mechanistic investigations revealed that the bifunctional phosphonium salt controlled the regio- and stereoselectivities of this cascade reaction, particularly proceeding through the initial ketone α-addition followed by O-participated substitution; and the multiple hydrogen-bonding interactions between Brønstedacid moieties
Iridium-catalyzed highly chemoselective and efficient reduction of nitroalkenes to nitroalkanes in water
作者:Dong Xu、Yang Chen、Changmeng Liu、Jiaxi Xu、Zhanhui Yang
DOI:10.1039/d1gc01907d
日期:——
An iridium-catalyzed highly chemoselective and efficient transfer hydrogenation reduction of structurally diverse nitroalkenes was realized at very low catalyst loading (S/C = up to 10000 or 20 000), using formic acid or sodium formate as a traceless hydride donor in water. Excellent functionality tolerance is also observed. The turnover number and turnover frequency of the catalyst reach as high as
在非常低的催化剂负载量(S/C = 高达 10000 或 20 000)下,使用甲酸或甲酸钠作为水中的无痕氢化物供体,实现了铱催化的高化学选择性和高效转移氢化还原结构多样的硝基烯烃。还观察到优异的功能耐受性。催化剂的周转次数和周转频率高达18 600和19 200 h -1, 分别。不需要惰性气氛保护。硝基烯烃的反应性取决于它们的取代模式,pH 值是实现完全转化和优异化学选择性的关键因素。产品的纯化通过简单的萃取实现,无需柱层析。还原过程在 10 000 S/C 比率下轻松放大到 10 g 规模。这种绿色还原在对映选择性氢化中的潜力已经得到证实。