10.1016/j.tetlet.2014.02.046
The study presents an innovative method for the 1,4-addition of arylboronic acids to α,β-unsaturated substrates using nickel(I) complexes as catalysts. The nickel(I) species were generated in situ from Ni(PPh3)2Cl2 with the aid of activated iron, and the catalytic system was combined with NN'-bis(4-fluorobenzylidene) ethane-1,2-diamine (BFBED). The reaction is completed without the need for a base, but the presence of potassium iodide is essential. The study suggests a possible Ni(I)–Ni(III) catalytic cycle mechanism and demonstrates the efficiency of the method with yields up to 76%. The scope of the reaction was explored with various substrates and arylboronic acids, showing no significant influence from electron-withdrawing or electron-donating groups. The work provides a valuable contribution to the field of cross-coupling reactions, offering a more environmentally benign and cost-effective alternative to traditional noble metal catalysts.
10.1021/acs.orglett.1c00626
The research focuses on the development of a stereo- and regioselective cis-hydrophosphorylation reaction of 1,3-enynes using visible-light irradiation of NiCl2(PPh3)2 as a catalyst. This reaction provides access to a variety of 1,3-dienes with good isolated yields. The experiments involved the use of NiCl2(PPh3)2, 1,10-phenanthroline as a ligand, Cs2CO3 as a base, and MeOH as a solvent. The reaction conditions were optimized to achieve the best yield of the desired (E)-1,3-diene products. Various 1,3-enynes and phosphine oxides were tested to establish the scope of the reaction. Analytical techniques such as NMR spectroscopy and X-ray crystallography were employed to determine the product yields, configurations, and structures. Preliminary mechanistic studies, including deuteration experiments and radical initiator tests, suggested a radical reaction pathway involving the generation of nickel phosphine species and their addition to the C≡C bond of the 1,3-enynes, followed by protonation to yield the cis-hydrophosphorylation products.
10.1039/c8ob00781k
The research focuses on the development of a highly efficient and straightforward method for the synthesis of multi-substituted allenes, which are important structural motifs found in natural and pharmaceutical products and serve as building blocks for various organic transformations. The study utilizes a nickel-catalyzed SN2' substitution reaction of propargyl esters with organic aluminum reagents under mild conditions, yielding multi-substituted allenes with good to excellent yields (up to 92%) and high selectivities (up to 99%). The chemicals involved in this process include nickel catalysts such as Ni(PPh3)2Cl2, phosphine ligands like PPh3, organic aluminum reagents such as AlMe3, and a variety of propargyl esters, which bear different substituents like electron-donating or electron-withdrawing groups, thienyl, pyridyl, and alkyl groups. The methodology provides a useful procedure for the synthesis of tri- and tetra-substituted allenes and demonstrates good tolerance for different propargyl esters. The research concludes that the developed method is effective for the synthesis of allenes and is currently exploring the application of this catalyst to other organoaluminum reagents and propargyl esters.