180071-98-1Relevant articles and documents
First Examples of Transition-Metal Free Sonogashira-Type Couplings
Leadbeater, Nicholas E.,Marco, Maria,Tominack, Bonnie J.
, p. 3919 - 3922 (2003)
(Matrix presented) We report here our observation that, using appropriate reaction conditions, the Sonogashira reaction can be performed without the need for transition-metal catalysts. Our approach involves the use of water as a solvent, poly(ethylene glycol) as a phase-transfer agent, and sodium hydroxide as a base. The methodology works, to differing extents, for aryl iodides and bromides.
Green synthesis of graphene oxide (GO)-anchored Pd/Cu bimetallic nanoparticles using: Ocimum sanctum as bio-reductant: An efficient heterogeneous catalyst for the Sonogashira cross-coupling reaction
Borah, Geetika,Gogoi, Pradip K.,Hussain, Farhaz Liaquat,Mech, Swapna Devi,Pahari, Pallab,Sultana, Samim
, p. 23108 - 23120 (2020/07/03)
To explore the synergism between two metal centers we have synthesized graphene oxide (GO) supported Pd/Cu?GO, Pd?GO and Cu?GO nanoparticles through bio-reduction of Pd(NO3)2 and CuSO4·5H2O using Tulsi (Ocimum sanctum) leaf extract as the reducing and stabilizing agent. The graphene oxide (GO) was obtained by oxidation of graphite following a simplified Hummer's method. The as-prepared nanomaterials have been extensively characterized by FTIR, powder X-ray diffraction (PXRD), HRTEM, TEM-EDS, XPS, ICP-AES and BET surface area measurement techniques. The morphological study of Pd/Cu?GO revealed that crystalline bimetallic alloy type particles were dispersed on the GO layer. The activity of Pd?GO, Cu?GO and Pd/Cu?GO as catalysts for the Sonogashira cross-coupling reaction have been investigated and it was found that the Pd/Cu?GO nanostructure showed highly superior catalytic activity over its monometallic counterparts, substantiating the cooperative influence of the two metals. The inter-atom Pd/Cu transmetalation between surfaces was thought to be responsible for its synergistic activity. The catalyst showed higher selectivity towards coupling of aryl iodides with both aliphatic and aryl alkynes resulting in moderate to excellent isolated yield of the desired products (45-99%). The products have been characterized by GC-MS and 1H-NMR spectroscopic techniques and compared with authentic samples. The Pd/Cu?GO catalyst could be easily isolated from the reaction products and reused for up to at least ten successive runs effectively.
Alkylation of Terminal Alkynes under Zinc Lewis Acid Catalysis and Its Mechanistic Studies
Osano, Mana,Kida, Takeru,Yonekura, Kyohei,Tsuchimoto, Teruhisa
supporting information, p. 2825 - 2831 (2019/04/13)
With a zinc Lewis acid catalyst and proton sponge in toluene, terminal alkynes were found to undergo the alkylation by alkyl triflates to provide unsymmetrical internal alkynes. This is the first example that a simple alkyl chain other than benzylic and norbornyl units can be introduced onto the alkynyl carbon atom under Lewis acid catalysis. Mechanistic studies revealed that the activation of the alkyne by the zinc Lewis acid and proton sponge is the trigger of the reaction to give a monoalkynylzinc species, which successively reacts with the alkyl triflate to afford the internal alkyne. A radical pathway is unlikely in this system. (Figure presented.).
