Activation of carbon dioxide: nickel-catalyzed electrochemical carboxylation of diynes
摘要:
The simultaneous activation of carbon dioxide and diynes by electrogenerated LNi(0) complexes (L = bpy, pentamethyldiethylenetriamine: PMDTA) enables the selective incorporation of one molecule of CO2 into the unsaturated systems and the preparative-scale electrosyntheses of carboxylic acids. A series of nonconjugated diynes afforded selectively linear or cyclic adducts depending on the ligand. Diynes bearing both a terminal and an internal triple bond gave exclusive CO2 incorporation into the terminal alkynyl group, regioselectively at the 2-position. The electrocarboxylation of 1,3-diynes with the Ni-PMDTA catalytic system yielded, regio- and stereoselectively, (E)-2-vinylidene-3-yne carboxylic acids in one step. The electrosyntheses were carried out in single-compartment cells fitted with a consumable magnesium anode, and utilized a catalytic amount of an air-stable Ni(II) complex as the catalyst precursor. Cyclic voltammetry studies revealed that both carbon dioxide and the diynes are able to coordinate to LNi(0)-generated species in DMF.
3‐diynes is described. Key for the success of this novel transformation is the utilization of an advanced palladium catalyst system with the specific ligand Neolephos. The synthetic value of this general approach to synthetically useful α‐alkynyl‐α, β‐unsaturated amides is showcased by diversification of several structurally complex molecules and marketed drugs. Control experiments and density‐functional
Remote ether groups-directed regioselective and chemoselective cycloaddition of azides and alkynes
作者:Xuelun Duan、Nan Zheng、Ming Li、Xinhao Sun、Zhuye Lin、Pan Qiu、Wangze Song
DOI:10.1016/j.cclet.2021.05.037
日期:2021.12
5-regioselectivities and excellent chemoselectivities. Ether group could coordinate with iridium catalyst by lone-pair electron at a distance (up to four σ bonds) away from alkyne to control the regioselectivity by weak coordination effect. The cycloaddition reaction chemoselectively occurred at the propargyl ether moiety of diyne to give unique fully substituted 4-alkynyl-triazole.
d selective hydroarylation of unsymmetrical alkynes represents the state‐of‐art in organic chemistry, and still mainly relies on the use of precious late‐transition‐metal catalysts. Reported herein is an unprecedented MnI‐catalyzed hydroarylation of unsymmetrical 1,3‐diyne alcohols with commercially available arylboronic acids with predictive selectivity. This method addresses the challenges in regio‐
Glaser–Hay hetero-coupling in a bimetallic regime: a Ni(<scp>ii</scp>)/Ag(<scp>i</scp>) assisted base, ligand and additive free route to selective unsymmetrical 1,3-diynes
作者:Anuradha Mohanty、Sujit Roy
DOI:10.1039/c7cc05605b
日期:——
A Ni(OAc)2/Ag(OTf) catalysed coupling of aryl alkynes and propargylic alcohol/ether/ester gave the corresponding unsymmetrical 1,3-diynes in good to excellent yields.
Investigation of an Efficient Palladium-Catalyzed C(sp)−C(sp) Cross-Coupling Reaction Using Phosphine−Olefin Ligand: Application and Mechanistic Aspects
作者:Wei Shi、Yingdong Luo、Xiancai Luo、Lei Chao、Heng Zhang、Jian Wang、Aiwen Lei
DOI:10.1021/ja8049436
日期:2008.11.5
A pi-acceptor phosphine-electron-deficient olefin ligand was found effective in promoting Pd-catalyzed C(sp)-C(sp) cross-coupling reactions. The new protocol realized the cross-coupling of a broad scope of terminal alkynes and haloalkynes in good to excellent yields with high selectivities. Electron-rich alkynes, which are normally difficult substrates in Glaser couplings, could be employed as either