Selective and Efficient Cycloisomerization of Alkynols Catalyzed by a New Ruthenium Complex with a Tetradentate Nitrogen-Phosphorus Mixed Ligand
作者:Pei Nian Liu、Fu Hai Su、Ting Bin Wen、Herman H.-Y. Sung、Ian D. Williams、Guochen Jia
DOI:10.1002/chem.200903441
日期:——
The new ruthenium complex [Ru(N3P)(OAc)][BPh4] (4), in which N3P is the N,P mixed tetradentate ligand N,N‐bis[(pyridin‐2‐yl)methyl]‐[2‐(diphenylphosphino)phenyl]methanamine was synthesized. The complex was found to be catalytically active for the endo cycloisomerization of alkynols. The catalytic reactions can be used to synthesize five‐, six‐, and seven‐membered endo‐cyclic enol ethers in good to
Preparation and reactivity of α-phenylselenenyl ethers
作者:David J. Goldsmith、Dennis C. Liotta、Mark Volmer、William Hoekstra、Liladhar Waykole
DOI:10.1016/s0040-4020(01)96726-2
日期:1985.1
α-Phenylsclenenyl cyclic ethers may be prepared by the reactions of either lactols or lactol acetates with benzeneselenol, or from lactones by the “one-pot” process of reduction and Lewis acid catalyzed selenation. The tetrahydropyranyl phenyl selenides also exhibit a significant anomeric effect and its size has been estimated. The selenenyl ethers are converted to enol ethers through an oxidative elimination
Visible‐Light‐Promoted Ring‐Opening Alkynylation, Alkenylation, and Allylation of Cyclic Hemiacetals through β‐Scission of Alkoxy Radicals
作者:Jiang‐Ling Shi、Zixuan Wang、Rui Zhang、Yuankai Wang、Jianbo Wang
DOI:10.1002/chem.201901762
日期:2019.7.5
The alkoxy radicals that are derived fromcyclic hemiacetals have been generated through the visible‐light‐promoted reaction of the corresponding N‐alkoxyphthalimides with Hantzsch ester as the reductant. The alkoxy radicals subsequently undergo β‐scission of the C−C bond to generate carbon‐centered radicals, which are trapped by alkynyl‐, alkenyl‐, or allylsulfones.
A series of hydrogen-atomtransfer (HAT) catalysts based on the readily available and tunable 1,4-diazabicyclo[2.2.2]octane (DABCO) structure was designed, and their photoinduced HAT catalysis ability was demonstrated. The combination of our HAT catalyst with an acridinium-based organophotoredox catalyst enables efficient and site-selective C–H alkylation of substrates ranging from unactivated hydrocarbons
设计了一系列基于容易获得且可调的 1,4-二氮杂双环[2.2.2]辛烷 (DABCO) 结构的氢原子转移 (HAT) 催化剂,并证明了它们的光诱导 HAT 催化能力。我们的 HAT 催化剂与基于吖啶的有机光氧化还原催化剂相结合,可以对从未活化的碳氢化合物到复杂分子的底物进行高效和位点选择性的 C-H 烷基化。值得注意的是,具有与氮原子相邻的附加取代基的 HAT 催化剂进一步提高了位点选择性。机理研究表明,催化剂的N取代基起着至关重要的作用,有助于生成双阳离子胺自由基作为 HAT 过程的活性物质。
Processes for preparing imidazole derivatives and salts thereof
申请人:YUHAN CORPORATION
公开号:US20030153769A1
公开(公告)日:2003-08-14
The present invention provides a process for preparing an imidazole derivative or its salt which comprises reacting a tetrahydrofuran or tetrahydropyran derivative with formamidine or its salt in the presence of a base.